To evaluate lesion detection of MRI in knee joint osteoarthritis in patients with symptoms of pain, the correlation between MRI findings and varying degrees of reported pain was assessed. Twenty-eight patients (31 knees) with osteoarthritis were recruited for this study. The degree of knee pain was assessed by VRS scores. The knees were evaluated by plain film radiograph utilizing Kellgren-Lawrence scores. Multiple MR sequences were performed on a 1.5T MR-system, including sagittal and coronal dual fast spin echo (TR/TE 3660/11/120 ms, slice thickness 5 mm), coronal spin echo T-1-weighted (TR/TE 360/9 ms, slice thickness 5 mm), sagittal fat saturated 3D-spoiled gradient-recalled echo (TR/TE 50/6 ms; slice thickness 1.5 mm; flip angle 40 degrees), and 3D steady-state free precession (TR/TE 6/2.2 ms; slice thickness 1.6 mm; flip angle 30 degrees) pulse sequences for the purpose of detecting abnormities of cartilage, menisci, the anterior cruciate ligaments, bone marrow edema-like lesions, osteophytes, synovitis, and joint effusions. MR findings were compared with the degree of pain using Fisher exact test with P values less than 0.05 indicating a statistically significant difference. The results showed that, of the 31 knees evaluated, mild pain was reported in 11 and severe pain in the remainder. Kellgren-Lawrence scores of all 31 evaluated OA knees were as follows: grade 1 lesions (n=6), grade 2 lesions (n=14), grade 3 lesions (n=8), and grade 4 lesions (n=3). Articular cartilaginous defects were found in 37.1% of knees. Abnormalities of the menisci and anterior cruciate ligaments, bone marrow edema-like lesions, osteophytes, synovitis, and joint effusions were detected in 32.3%, 38.7%, 45.2%, 100%, 15.1% and 67.7% of knees, respectively. Of these variables, only the differences in prevalence of joint effusions were significantly different in the mild and severe pain groups (P=0.004). It is concluded that MRI evaluates the entire joint structure of the osteoarthritic knee, demonstrating abnormalities of the cartilage, menisci, and anterior cruciate ligaments as well as bone marrow edema-like lesions, osteophytes, synovitis, and joint effusions. The difference in pain grading between OA patients reporting mild and severe degrees of pain is related to the presence of joint effusion.