The diagnostic criteria and nomenclature used to describe the painful stiff shoulder remain confused. Arthrographic features of capsulitis have come to be accepted as characteristic of the frozen shoulder. Increased technetium uptake has also been noted. Both features have been considered to have possible prognostic and therapeutic importance. During a therapeutic study of strictly defined clinical frozen shoulder 35 of 38 patients showed increased technetium diphosphonate uptake in the affected shoulder in comparison with the opposite side. Of 36 patients who had arthrography 15 showed evidence of capsulitis, 11 rupture of the rotator cuff, and five no abnormality. Five tests failed owing to technical difficulty. There was no association between the technetium uptake and the arthrographic features, and neither was useful in predicting the rate or extent of recovery. Frozen shoulder of traumatic onset behaved no differently from that which arose spontaneously. We do not therefore consider that arthrography or technetium diphosphonate scanning performed at presentation contributes to the assessment of the painful stiff shoulder.