Quinolones have been reported to be active against BruceUla species in vitro. In this prospective randomized study, the efficacy and safety of the combination of ofloxacin plus rifampin were compared with the efficacy and safety of doxycycline plus rifampin, both combinations administered for a 6-week period in treatment of brucellosis. Sixty-one patients were enrolled in the study, and 49 had blood or bone marrow cultures positive for BruceUla melitensis. Thirty patients received 200 mg of doxycycline plus 600 mg of rifampin once daily, and 31 patients were treated with 400 mg of ofloxacin plus 600 mg of rifampin once daily for 6 weeks. Nine patients in each group had complications of the disease. There was one therapeutic failure in the ofloxacin-rifampin treatment group, and one patient from each group relapsed (3.3% of those in the doxycycline-rifampin treatment group versus 3.2% of those in the ofloxacin-rifampin treatment group). Gastric discomfort was the major side effect observed in 13 patients (43.3%) who received doxycycline plus rifampin, whereas only 2 patients (6.5%) treated with ofloxacin plus rifampin complained of gastric irritation. These results suggest that the combination of ofloxacin plus rifampin administered for 6 weeks is as effective as doxycycline plus rifampin given for the same period, regardless of the presence of complications of the disease.Brucellosis is a major health problem worldwide, especially in developing countries. The best regimen for the treatment of acute brucellosis is not clearly determined (2). Brucella species are facultative intracellular parasites; therefore, complete eradication of the microorganism is difficult to achieve, and relapses are common.The fluoroquinolones have excellent bactericidal activity against a variety of bacteria. In addition, they penetrate well into leukocytes and macrophages, which makes them suitable agents in treatment of intracellular infections. Several studies have reported the in vitro activity of quinolones against Brucella species (6,12,13,15,22 employed in the regimens were also not included in the study.The diagnostic criteria were a standard tube agglutination titer of 1/160 or more for anti-Brucella antibodies in the presence of compatible clinical findings (fever, night sweats, arthralgia, hepatomegaly, splenomegaly, and lymphadenopathy) and isolation of a Brucella sp. from blood or bone marrow cultures.Sacroiliitis, spondylitis, peripheral arthritis, and orchitis were defined by appropriate findings on physical examination and relevant radiographic, radionuclide, and tomographic studies. Briefly, pain over the involved vertebral bodies or sacroiliac joints, accompanied by isotope accumulation in a radionuclide scan, was defined as sacroiliitis or spondylitis. Narrowing and/or irregularity of the sacroiliac articular spaces in plain X-ray films were considered to support the diagnosis of sacroiliitis.