Background: Magnetic Resonance Imaging (MRI) of the knee joint has often been regarded as the noninvasive alternative to diagnostic arthroscopy. New technology, however, masks the importance of history and physical examination. This study aims at evaluating the accuracy of physical examination and MRI scanning in diagnosis of knee injury, including meniscal tears and cruciate ligaments ruptures.Methods: In a cross-sectional, analytic-descriptive study, 120 patients (108 males, 12 females) with knee injury who were candidates for arthroscopy were recruited in a Hospital in Tabriz during a one-year period. Prior history of arthroscopy or knee surgery was considered as exclusion criteria. A complete history and physical examination was performed and diagnosis was documented before looking at the MRI results. The final arthroscopic diagnosis was then compared with clinical and MRI studies.Results: 120 knee injury cases with a mean age of 29 (16-54) years were enrolled. Accuracy, sensitivity and specificity of clinical examination was respectively 85, 94.8 and 75.8 percent for medial meniscus, 85, 70.8 and 88.5 percent for lateral meniscus, 95.8, 98.6 and 91.7 percent for anterior cruciate ligament and 100 percent for posterior cruciate injuries. Accuracy, sensitivity and specificity of MRI were respectively 77.5, 84.2 and 71.4 percent for medial meniscal. 85.8, 56.5 and 92.8 percent for lateral meniscal, 92.5, 98.6 and 83.3 percent for anterior cruciate, and 100 percent for posterior cruciate injuries. Overall, in isolated injuries, the accuracy of clinical examination was relatively better than MRI in complex injuries, while MRI had higher accuracy in complex intra-articular injuries.Conclusion: According to our results, both physical examination and MRI scanning are very sensitive and accurate in diagnosis of knee injuries, with a slight preference of physical examination. MRI should be reserved for doubtful or complex injuries.