Growth hormone (GH) replacement seems to represent an additional risk factor for epiphysiolysis. The femoral diaphyseal-epiphyseal angle (Southwick's angle), which is observed to become decreased in the presence of slipped capital femoral epiphysis, is increased in risk groups, such as obese patients, suggesting a potential marker for epiphysiolysis. To evaluate the pattern of Southwick's angle in GH deficiency (GHD) patients, we measured it in 44 GHD patients. We found that Southwick's angle increased significantly after 2 years on GH replacement compared with the pretreatment period. Our data suggest that increasing in Southwick's angle during GH treatment might represent an increased risk for epiphysiolysis in GHD patients.