Aim: In this paper, we present the hematological findings of 787 cases diagnosed with acute brucellosis. Materials and Methods: Records of the cases seen between 1994 and 2006 were retrospectively investigated regarding hematological changes. Results: Three hundred sixty-five (46%) patients were male and 422 (54%) were female. Mean age was 32 (range: 11-78 years). Mean hematological values were as follows: Hb 12 g/dl (4-19), Htc 36% (12-56), leukocyte 6.9 × 109/L (0.5-25) and platelets 213 × 109/L (9-617). According to differential counts, 34% and 14% of patients had mononuclear cell and neutrophil dominance, respectively. Fifty-six percent of patients were found to have anemia, alone or in combination with leukopenia or thrombocytopenia. Fourteen percent of patients had thrombocytopenia, 12% leukopenia, 5% pancytopenia, 4% leukopenia + thrombocytopenia, 0.5% acute hemolysis, and 0.1% disseminated intravascular coagulation. Restoration of thrombocytopenia and leukopenia and improvement in clinical situation were seen within one week and recovery of anemia occurred within 3-4 weeks. Conclusions: Hematological complications such as anemia and leukopenia are more frequently seen in acute brucellosis cases. However, acute brucellosis should also be considered in the differential diagnosis in the presence of other hematological abnormalities such as severe thrombocytopenia, pancytopenia, acute hemolytic anemia, and disseminated intravascular coagulation.