The present study was undertaken to evaluate efficacy, safety and patient acceptability of three antibiotic regimens for the treatment of acute brucellosis. Six different centres were involved: three in France, one in Greece and two in Spain. The regimens were: oral rifampicin 900 mg/day plus oral doxycycline 200 mg/day for 45 days (A), oral doxycycline 200 mg/day for 45 days plus im streptomycin 1 g/day for 21 days (regimen B) [corrected] and the WHO regimen (C) combining oral tetracycline 2 g/day for 21 days plus im streptomycin, 1 g/day, for 14 days. Regimens A and B were randomly allocated in all centres, while regimen C was allocated only in two centres. All patients were suffering from acute brucellosis clinically and biologically proven. 143 patients were allocated for treatment and analysed. Their mean age was 41 years (range 13-70), 49 were female and 94 male, and their mean weight was 64 kg (range 35-98). Among these patients, 14% had localized disease (nine orchitis, eight osteo-articular involvement and one pleural effusion), but there was no statistical difference between the three regimens in regard to this localized disease. Forty-five per cent of the patients had positive blood cultures. The cure rate with regimen A was 95%, 96% with regimen B and 59% with regimen C. Thus regimen A presented the same efficacy rate as regimen B, but regimen C cannot be regarded as the treatment of choice for acute brucellosis.