Progression of slipped capital femoral epiphysis following in situ screw fixation typically occurs through loosening of the screw in the metaphysis. Epiphyseal migration off the screw due to physeal growth is rare. We report epiphyseal migration off bilateral screws in a child undergoing thyroid replacement therapy. Patients with mild and moderate slipped capital femoral epiphysis and endocrine disease should be followed-up with radiographs taken at intervals which reflect the rate of growth. Fixation should be revised if the tip of the screw approaches the physis and initial fixation with two screws may be considered.