PURPOSE: To determine the metaphyseal changes occurring in Legg-Calve-Perthes(LCP) disease using MRI. MATERIALS AND METHODS: Between 1992 to 1999, 80 LCP patients (87 hips) underwent MR imaging and plain radiography. All MR images were reviewed, bone marrow signal intensity, the size and location of the metaphyseal cyst and its epiphyseal necrosis grade determined. RESULTS: Metaphyses were abnormal in 43hips (49%), while bone marrow edema was present in 28 (32%) and a metaphyseal cyst in 30 (34%). Metaphyseal cysts were classified as either 'true' (n=9) or 'false' (n=21) according to the enhancement pattern. The maximum diameters of true and false cysts were 1.1+/-0.3 cm and 1.1+/-0.4 cm, respectively. Their most commom location was the anterior column; a true cyst occurred there in 7cases (78%), and false cyst in 16 (76%). Using the Waldenstrom classification, seven of the nine hips wih a true cyst (78%), were found to be at the avascular stage and 15 of the 21 with a false cyst (71%) were at the fragmentation stage. Seven of these nine (78%) and 19 of these 21 (90%) were Catterall grade IV. CONCLUSION: According to the findings of MR imaging, the metaphyseal changes occurring in LCP disease were bone marrow edema and metaphyseal cyst. This latter was visualized mainly in the anterior column and severely affected hip, and was classified as 'true' or 'false'.