Background:We conducted a retrospective cohort study to evaluate the clinical manifestations, laboratory findings, complications and treatment of brucellosis in the State of Qatar.Methods:The medical records of patients in Hamad Medical Corporation, Doha, Qatar were reviewed from January 2000 to December 2006. History, various socio-demographic features, clinical and biochemical parameters, therapeutic features, and complications were retrospectively collected from the patient database.Results:Around three quarters of the study population were males. History of raw milk consumption and animal contact were seen in 41.7% and 12.5% respectively. The main presenting features of our cohort were fever, chills and sweating (93.1%, 62.5% and 58.3% respectively). Positive antibody titre (>1:160) was detected in 95.8% and positive blood culture was reported in 63.9% of the cohort. Splenomegaly was observed in 19.4%, hepatomegaly in 15.3% and lymphadenopathy in 9.7% of the cases. Approximately half of our patients were treated with a combination of doxycycline and streptomycine and nearly one quarter received doxycycline and rifampicine combination therapy.Conclusions:Brucellosis is an important public health problem worldwide. It is associated with significant morbidity and mortality. It may affect any organ system and can present with a variety of clinical features. Diagnosis of brucellosis requires serological tests with or without blood culture. Treatment with at least two antibiotics for six weeks or more appears to be effective.