The clinical pattern of 400 cases of brucellosis in Kuwait is presented. The disease was acute in 77 per cent, sub-acute in 12.5 per cent and chronic in 10.5 per cent of cases. Raw milk was the major source of infection. The major features on presentation, irrespective of the course of the disease, were fever, sweating, headache, rigors, arthralgia, myalgia, and low back pain. Hepatosplenomegaly was present in 41 per cent of cases and in 32 per cent neither liver nor spleen were palpable. The haematologic findings were not specific and hepatic dysfunction (shown by liver enzyme abnormalities) was common. Skeletal (26 per cent) and genital (8.5 per cent) changes and neurobrucellosis (7 per cent) were the major complications. The ELISA was the most sensitive and reliable diagnostic test especially in relation to chronic brucellosis and neurobrucellosis. ELISA allowed the determination of brucella-specific immunoglobulins (Ig)G, IgM and IgA in the CSF, and provided profiles of Ig, in sera, which were different in patients with chronic (elevated IgG and IgA) from those with acute (elevated IgM alone or IgG, IgM and IgA) brucellosis. Treatment with tetracycline, doxycycline or rifampicin gave a cure rate of over 91 per cent in acute and subacute brucellosis. Co-trimoxazole was associated with a relapse rate of 50 per cent. Two drug combinations of streptomycin and tetracycline, streptomycin and rifampicin or streptomycin and doxycycline were effective, but one of five patients with chronic brucellosis relapsed. A combination of streptomycin, tetracycline and rifampicin with or without steroids was used successfully in neurobrucellosis, septicaemic shock and subacute bacterial endocarditis.