A case of slipped capital femoral epiphyses is reported which occurred in association with primary hyperparathyroidism. Only two similar cases have been found in the English literature. The patient was a man, 16 years of age, who presented with bilateral slipped epiphyses. Investigation showed that he had primary hyperparathyroidism due to a parathyroid adenoma. At a single operation, the epiphyses were pinned in situ, and the adenoma removed. The result was satisfactory.