diff --git a/Orange/widgets/data/owfile.py b/Orange/widgets/data/owfile.py
index fd2ca9e4247..689862c31b2 100644
--- a/Orange/widgets/data/owfile.py
+++ b/Orange/widgets/data/owfile.py
@@ -91,7 +91,7 @@ class OWFile(widget.OWWidget, RecentPathsWComboMixin):
     want_main_area = False
 
     SEARCH_PATHS = [("sample-datasets", get_sample_datasets_dir())]
-
+    SIZE_LIMIT = 1e7
     LOCAL_FILE, URL = range(2)
 
     settingsHandler = PerfectDomainContextHandler()
@@ -118,6 +118,10 @@ class OWFile(widget.OWWidget, RecentPathsWComboMixin):
                   for f in sorted(set(FileFormat.readers.values()),
                                   key=list(FileFormat.readers.values()).index)))
 
+    class Warning(widget.OWWidget.Warning):
+        file_too_big = widget.Msg("The file is too large to load automatically."
+                                  " Press Reload to load.")
+
     def __init__(self):
         super().__init__()
         RecentPathsWComboMixin.__init__(self)
@@ -214,10 +218,17 @@ def __init__(self):
         self.set_file_list()
         # Must not call open_file from within __init__. open_file
         # explicitly re-enters the event loop (by a progress bar)
-        QTimer.singleShot(0, self.load_data)
 
         self.setAcceptDrops(True)
 
+        reader = self._get_reader()
+        if self.source == self.LOCAL_FILE and \
+                        os.path.getsize(reader.filename) > self.SIZE_LIMIT:
+            self.Warning.file_too_big()
+            return
+
+        QTimer.singleShot(0, self.load_data)
+
     def sizeHint(self):
         return QSize(600, 550)
 
@@ -263,7 +274,7 @@ def load_data(self):
         # file readers
         # pylint: disable=broad-except
         self.editor_model.set_domain(None)
-
+        self.Warning.file_too_big.clear()
         error = None
         try:
             self.reader = self._get_reader()
diff --git a/Orange/widgets/data/tests/test_owfile.py b/Orange/widgets/data/tests/test_owfile.py
index 8fae90a8318..761ace701eb 100644
--- a/Orange/widgets/data/tests/test_owfile.py
+++ b/Orange/widgets/data/tests/test_owfile.py
@@ -64,4 +64,8 @@ def _drop_event(self, url):
             QPoint(0, 0), Qt.MoveAction, data,
             Qt.NoButton, Qt.NoModifier, QDropEvent.Drop)
 
-
+    def test_check_file_size(self):
+        self.assertFalse(self.widget.Warning.file_too_big.is_shown())
+        self.widget.SIZE_LIMIT = 4000
+        self.widget.__init__()
+        self.assertTrue(self.widget.Warning.file_too_big.is_shown())