Calcific tendinitis of the gluteus maximus tendon is unusual and only eight cases associated with erosions of cortical bone have been reported. We present three further cases which demonstrate variation in appearances of the amorphous calcification in the tendon and cortical erosions on plain radiographs. Isotope bone scans show focal increased activity and computed tomography (CT) clearly demonstrates erosion of cortical bone and calcification within the tendon insertion of gluteus maximus. Follow-up examinations in two cases demonstrated resolution of the changes. We believe this series demonstrates the radiological features and natural history of a common condition occurring at an unusual site. Its recognition is important in order to avoid unnecessary surgical intervention. Resolution of the calcification and cortical erosions has not been previously described.