Background: Sonoelastography is a growing tool in evaluation of tendon pathologies. Due to its superficial position, patellar tendon pathology can be well evaluated by superficial ultrasound (US) and sonoelastography. Evaluation of tendon pathology is best done with magnetic resonance imaging. Objective: Toevaluation of the accuracy of sonoelastography compared to MRI in patellar tendon lesions. Patients and methods: Forty eight patients (25 males, 23 females) with patellar tendon lesion were referred from the Department of Orthopedic Surgery and Rheumatology Outpatient Clinics. The patient's mean age was 42.85 (ranged from 12 to 68) years. All patients were evaluated by US, sonoelastography and MRI. Results: The mean modulus of elasticity of the patellar tendon in this study was 114.4 kPa ranging from 70-186 kPa. There were three cases that were wrongly diagnosed as patellar tendon lesion by US and sonoelastography but they showed no abnormality in MRI [no tendon thickening or signal intensity changes]. The percentage of true positive cases was 93.8% compared to 6.2% false positive cases. Conclusion: When compared to magnetic resonance imaging (MRI), shear-wave elastography provides adequate accuracy (93.8%) when measuring patellar tendon stiffness.