Septic arthritis is a common, often disabling disease that requires early diagnosis for optimal outcome. The purpose of this study is to assess the efficacy and diagnostic accuracy of Magnetic Resonance Imaging in assessment of patients with septic arthritis. This study included 34 patients; the final diagnosis by culture and sensitivity was 28 septic arthritis and 6 patient was diagnosed as non septic joint. The MRI was diagnosed 27 out of 28 as septic arthritis and diagnosed all of the 6 non septic joint as transient synovitis. We found that sensitivity and specificity of post contrast MRI with fat suppression are 96.4% and 100%, respectively, for the detection of septic arthritis.