diff --git a/MovieExtendsBox.go b/MovieExtendsBox.go
new file mode 100644
index 0000000..01f3305
--- /dev/null
+++ b/MovieExtendsBox.go
@@ -0,0 +1,55 @@
+// Copyright 2024 Martin Riedl
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gomp4
+
+// MovieExtendsBox Movie Extends Box struct
+//
+// 8.8.1 Movie Extends Box
+//
+// Box Type: ‘mvex’
+// Container: Movie Box (‘moov’)
+// Mandatory: No
+// Quantity: Zero or one
+//
+// This box warns readers that there might be Movie Fragment Boxes in this file. To know of all samples in
+// the tracks, these Movie Fragment Boxes must be found and scanned in order, and their information
+// logically added to that found in the Movie Box.
+type MovieExtendsBox struct {
+	*Box
+	ChildBoxes []any
+}
+
+// BoxTypeMovieExtends Movie Extends Box
+const BoxTypeMovieExtends = "mvex"
+
+func init() {
+	BoxDefinitions = append(BoxDefinitions, BoxDefinition{
+		Type:        BoxTypeMovieExtends,
+		ParentTypes: []string{BoxTypeMovie},
+		Parser:      ParseMovieExtendsBox,
+	})
+}
+
+// ParseMovieExtendsBox creates a new movie extends box struct based on bytes
+func ParseMovieExtendsBox(parser *Parser, filePosition uint64, headerSize uint32, content []byte) (any, error) {
+	box := &MovieExtendsBox{
+		Box: &Box{filePosition, headerSize},
+	}
+
+	// parse child boxes
+	var err error
+	box.ChildBoxes, err = box.parseChildBoxes(parser, BoxTypeMovieExtends, filePosition, content)
+	return box, err
+}
diff --git a/README.md b/README.md
index 4921ee6..e48f07b 100644
--- a/README.md
+++ b/README.md
@@ -56,7 +56,7 @@ Implementation progress of ISO/IEC 14496-12:2015:
 | 8.7.7 Sub-Sample Information Box                   | subs           |      - |
 | 8.7.8 Sample Auxiliary Information Sizes Box       | saiz           |      - |
 | 8.7.9 Sample Auxiliary Information Offsets Box     | saio           |      - |
-| 8.8.1 Movie Extends Box                            | mvex           |      - |
+| 8.8.1 Movie Extends Box                            | mvex           |   100% |
 | 8.8.2 Movie Extends Header Box                     | mehd           |      - |
 | 8.8.3 Track Extends Box                            | trex           |      - |
 | 8.8.4 Movie Fragment Box                           | moof           |   100% |