The initial clinical symptoms, the course of the disease, and the effect of corticosteroid treatment have been analyzed in a retrospective study of 63 patients with temporal arteritis or polymyalgia rheumatica. The relationship between the physical examination of the temporal regions, the ophthalmological examination, and biopsy from the temporal artery with respect to the diagnostic value were examined. Histological examination of biopsy specimens from the temporal artery in 58 patients revealed arteritis in 46. Half of the patients had only local symptoms from the temporal regions; one fourth presented such symptoms as well as myalgias, and one fourth had myalgias only. Patients presenting local symptoms of temporal arteritis as well as of myalgias had always had myalgias as the initial symptom and developed local symptoms of temporal arteritis 1-24 months later. Permanent reduction of vision occurred in 20% of the patients. Symptoms of generalized arteritis were observed in several patients. The overlapping of the clinical symptoms, the positive biopsy findings in patients with polymyalgia rheumatica as the only local symptom and the identical reaction to corticosteroid treatment support the conception of temporal arteritis and polymyalgia rheumatica as two manifestations of the same disease. The physical and the ophthalmological examinations were of limited diagnostic value. Positive biopsy findings were seen in 25 patients with noraml palpatory findings, and in 46 patients without eye symptoms the ophthalmoscopic examination revealed no signs of arteritis. If the first biopsy from the temporal artery is negative, biopsy from the contralateral temporal artery should be performed. Correctly timed corticosteroid treatment in adequate doses can prevent reduction of vision in giant-cell arteritis. The treatment is a long-term therapy, its average duration in the present study being more than two years.