Two hundred and sixty three patients with a diagnosis of brucellosis between January 1984 and December 1987 were studied prospectively. Sixty five patients (25%) developed osteoarticular complications. These patients had a more prolonged course than those with no complications. Spondylitis in 38 (58%) and sacroiliitis in 29 (45%) were the most prevalent. There were no significant laboratory, serological, or bacteriological differences between patients with and without osteoarticular complications. At diagnosis 47 patients (72%) showed radiographic abnormalities, commonly in axial sites but rarely in peripheral sites. Radionuclide bone scan was positive with no radiographic abnormalities in 17 (26%) of cases. Fifty seven patients received medical treatment alone, 51 (89%) being cured with a single course of treatment. Treatment failed or there was a relapse in six patients (11%), of whom five had spondylitis. Eight of the 65 patients (12%), all of whom had spondylitis and paravertebral or epidural abscesses, also required surgical treatment.