To assess the accuracy of cartilage thickness measurements in magnetic resonance imaging (MRI), we compared data obtained by cartilage thickness measurements in MRI with corresponding histological sections of 14 human proximal tibial articular surfaces. Each proximal tibial articular surface was cut into five medial and lateral slices and each of these slices was divided into three sectors providing 420 sectors, 406 of which were evaluated in our study. The overall correlation coefficient (r) was 0.96. Topographical differences were found. The lowest correlation coefficient in our series was observed in the anterior part of the medial tibial plateau (r = 0.88). Cartilage thickness measurements in MRI were more accurate in cartilage thicker than 2 mm (r = 0.94) than in thinner cartilage layers (r = 0.73). There were no significant differences in cartilage thickness measurements in different grades of osteoarthritis. However, the mean percentage difference between cartilage thickness in MRI and histology was about 10% in our series.