We present rare case of medial meniscus dislocation, in a 25 years old female patient who was admitted in emergency department. With painful locked left knee. Arthroscopy was done next day showing isolated dislocation of medial meniscus with the absence of any medial meniscus tear. Only reduction of the medial meniscus was done. Postoprative MRI confirmed the diagnosis and showed no tears in the medial meniscus. Physiotherapy and clinical follow up were done with good results and no recurrence for 4 months postoperative.