Four patients with acute brucellosis are described, none of whom had any connexion with farming or milk industry, the source of infection being different in each case. The diagnosis was made by serological tests, and in three of the four cases was confirmed by positive cultures from bone marrow (one case) and liver biopsy (two cases). Treatment with the combination of trimethoprim/sulphamethoxazole was successful in three out of four cases, and in the fourth case failure may have been due to the development of trimethoprim resistance.