Opinions differ concerning the treatment of choice for severe slipped capital femoral epiphysis, probably due to the lack of long-term follow-up evaluations on the different methods of treatment. A series of 33 patients with severe slipped capital femoral epiphysis, treated per primam with wedge osteotomy of the femoral neck, were radiographically and clinically reexamined an average of 28 years (range, 16-32 years) after the operation. Segmental collapse and/or chondrolysis developed in ten patients. Nine of these patients were available for reexamination and all had severe arthrosis with poor function. Arthrosis developed in nine of the 19 patients without signs of segmental collapse or chondrolysis; these patients had a satisfactory joint function. This series was compared with another series (from the same orthopedic departments) of patients with severe slip without any primary treatment. The long-term results in these two groups were similar; consequently, the value of realignment by wedge osteotomy of the femoral neck is questionable.