diff --git a/src/bitmap/mod.rs b/src/bitmap/mod.rs
index 9b34bdcd..c2c2ea8c 100644
--- a/src/bitmap/mod.rs
+++ b/src/bitmap/mod.rs
@@ -12,6 +12,7 @@ mod cmp;
 mod inherent;
 mod iter;
 mod ops;
+mod ops_with_serialized;
 #[cfg(feature = "serde")]
 mod serde;
 mod serialization;
diff --git a/src/bitmap/ops_with_serialized.rs b/src/bitmap/ops_with_serialized.rs
new file mode 100644
index 00000000..5be221b6
--- /dev/null
+++ b/src/bitmap/ops_with_serialized.rs
@@ -0,0 +1,173 @@
+use bytemuck::cast_slice_mut;
+use byteorder::{LittleEndian, ReadBytesExt};
+use std::{
+    io::{self, Read},
+    mem::size_of,
+};
+
+use crate::RoaringBitmap;
+
+use super::{
+    container::Container,
+    store::{ArrayStore, BitmapStore, Store},
+};
+
+const SERIAL_COOKIE_NO_RUNCONTAINER: u32 = 12346;
+const SERIAL_COOKIE: u16 = 12347;
+
+impl RoaringBitmap {
+    pub fn union_with_serialized(&mut self, mut reader: impl Read) -> io::Result<()> {
+        let (size, has_offsets) = {
+            let cookie = reader.read_u32::<LittleEndian>()?;
+            if cookie == SERIAL_COOKIE_NO_RUNCONTAINER {
+                (reader.read_u32::<LittleEndian>()? as usize, true)
+            } else if (cookie as u16) == SERIAL_COOKIE {
+                return Err(io::Error::new(io::ErrorKind::Other, "run containers are unsupported"));
+            } else {
+                return Err(io::Error::new(io::ErrorKind::Other, "unknown cookie value"));
+            }
+        };
+
+        if size > u16::MAX as usize + 1 {
+            return Err(io::Error::new(io::ErrorKind::Other, "size is greater than supported"));
+        }
+
+        let mut description_bytes = vec![0u8; size * 4];
+        reader.read_exact(&mut description_bytes)?;
+        let mut description_bytes = &description_bytes[..];
+
+        if has_offsets {
+            let mut offsets = vec![0u8; size * 4];
+            reader.read_exact(&mut offsets)?;
+            drop(offsets); // Not useful when deserializing into memory
+        }
+
+        for _ in 0..size {
+            let key = description_bytes.read_u16::<LittleEndian>()?;
+            let len = u64::from(description_bytes.read_u16::<LittleEndian>()?) + 1;
+
+            if len <= 4096 {
+                match self.containers.binary_search_by_key(&key, |c| c.key) {
+                    Ok(loc) => {
+                        let container = &mut self.containers[loc];
+
+                        for _ in 0..len {
+                            let mut value = [0u8; size_of::<u16>()];
+                            reader.read_exact(value.as_mut())?;
+                            // TODO: since this is sorted it could probably be faster
+                            let value = u16::from_le_bytes(value);
+                            container.insert(value);
+                        }
+                    }
+                    Err(loc) => {
+                        let mut values = vec![0u16; len as usize];
+                        reader.read_exact(cast_slice_mut(&mut values))?;
+                        values.iter_mut().for_each(|n| *n = u16::from_le(*n));
+
+                        let array = ArrayStore::from_vec_unchecked(values);
+                        let mut container = Container::new(key);
+                        container.store = Store::Array(array);
+                        self.containers.insert(loc, container);
+                    }
+                }
+            } else {
+                match self.containers.binary_search_by_key(&key, |c| c.key) {
+                    Ok(loc) => {
+                        let current_store = std::mem::take(&mut self.containers[loc].store);
+
+                        let mut values = Box::new([0; 1024]);
+                        reader.read_exact(cast_slice_mut(&mut values[..]))?;
+                        values.iter_mut().for_each(|n| *n = u64::from_le(*n));
+
+                        let mut store = BitmapStore::from_unchecked(len, values);
+
+                        match current_store {
+                            Store::Array(array) => array.into_iter().for_each(|el| {
+                                store.insert(el);
+                            }),
+                            Store::Bitmap(bitmap_store) => store |= &bitmap_store,
+                        };
+
+                        self.containers[loc].store = Store::Bitmap(store);
+                    }
+                    Err(loc) => {
+                        let mut values = Box::new([0; 1024]);
+                        reader.read_exact(cast_slice_mut(&mut values[..]))?;
+                        values.iter_mut().for_each(|n| *n = u64::from_le(*n));
+
+                        let array = BitmapStore::from_unchecked(len, values);
+                        let mut container = Container::new(key);
+                        container.store = Store::Bitmap(array);
+                        self.containers.insert(loc, container);
+                    }
+                }
+            };
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::RoaringBitmap;
+    use proptest::prelude::*;
+
+    proptest! {
+        #[test]
+        fn prop_or_with_serialized(
+            mut a in RoaringBitmap::arbitrary(),
+            b in RoaringBitmap::arbitrary()
+        ) {
+            let union = &a | &b;
+
+            let mut b_ser = Vec::new();
+            b.serialize_into(&mut b_ser).unwrap();
+            a.union_with_serialized(&*b_ser).unwrap();
+
+            prop_assert_eq!(a, union);
+        }
+    }
+
+    #[test]
+    fn or_with_serialized() {
+        let unions = [
+            (RoaringBitmap::new(), RoaringBitmap::new()),
+            (RoaringBitmap::from_sorted_iter([0]).unwrap(), RoaringBitmap::new()),
+            (RoaringBitmap::new(), RoaringBitmap::from_sorted_iter([0]).unwrap()),
+            (
+                RoaringBitmap::from_sorted_iter([0]).unwrap(),
+                RoaringBitmap::from_sorted_iter([0]).unwrap(),
+            ),
+            (
+                RoaringBitmap::from_sorted_iter([0]).unwrap(),
+                RoaringBitmap::from_sorted_iter([1]).unwrap(),
+            ),
+            (
+                RoaringBitmap::from_sorted_iter([0]).unwrap(),
+                RoaringBitmap::from_sorted_iter(0..3000).unwrap(),
+            ),
+            (
+                RoaringBitmap::from_sorted_iter([]).unwrap(),
+                RoaringBitmap::from_sorted_iter(0..3000).unwrap(),
+            ),
+            (
+                RoaringBitmap::from_sorted_iter(0..3000).unwrap(),
+                RoaringBitmap::from_sorted_iter([3001]).unwrap(),
+            ),
+            (
+                RoaringBitmap::from_sorted_iter(0..3000).unwrap(),
+                RoaringBitmap::from_sorted_iter(3000..6000).unwrap(),
+            ),
+        ];
+
+        for (mut a, b) in unions {
+            let union = &a | &b;
+
+            let mut b_ser = Vec::new();
+            b.serialize_into(&mut b_ser).unwrap();
+            a.union_with_serialized(&*b_ser).unwrap();
+
+            assert_eq!(a, union, "When testing: {a:?} | {b:?}");
+        }
+    }
+}