Background: Patello-femoral stability is principally influenced by anatomic factors. Understanding the anatomy and biomechanics of the patello-femoral joint provides insight on the etiology and management of patellar instability. Magnetic resonance imaging (MRI) has emerged as an auxiliary method for investigating patello-femoral instability, particularly for detecting osteochondral lesions and for evaluating the medial patello-femoral ligament (MPFL). Objective: descriptive study including analysis of MRI knee done for patients with patellar instability suspected clinically with or without history of trauma. Patients and Methods: thirty patients were included in this study, all with suspicious patellar instability from Ain-Shams University, orthopedic clinic and other private clinics. A cross-sectional study was held where all the patients under-went MRI routine knee protocol. MRI knee images were interpreted for identification of different pathologies contributing to patellar instability. Results: sixty percent of the patients included in our study had MPFL injury, 43% showed patella alta, 83% showed trochlear dysplasia (by different measurements) and 43% showed lateral displacement of TT. Conclusion: MRI the modality of choice in diagnosing different pathologies of patellar instability, for its value in assessing soft tissue structures, detailed imaging of the cartilage and applying all measurement required.