Background: Brucellosis as a zoonotic disease is controlled in many developed countries though it still remains endemic in the majority of Middle Eastern and developing countries. Objectives: The purpose of this study was to identify the demographic features, clinical manifestations, and laboratory tests of patients diagnosed with brucellosis in Ghazvin province of Iran. Methods: In this cross-sectional study, medical records of 83 cases with brucellosis (54 males and 29 females) over a 3-year period (from June, 2012 to June, 2015) were reviewed, retrospectively. Demographic features, clinical signs and symptoms, hematologic findings, and liver enzyme level were derived from the patients' medical record. Results: The mean age of cases was 42.5±18.3 years. Constitutional symptoms, which were noted in 45 (54%) cases, were the most common symptom of the disease. Clinical manifestations, including Sacroileitis, arthritis, and epididymo-orchitis were seen in 20 (24.1%), 10 (12%), and 7 (8.4%) cases, respectively. One case of Endocarditis (1.2%) was noted. Anemia as the most frequent blood abnormality was seen in 44 (53%) cases. Leukopenia and leukocytosis were noted in 17 (20.5%) and 9 (10.8%) patients, respectively. Thrombocytopenia and thrombocytosis were detected in 26 (31.3%) and 3 (3.6%) of the patients, respectively. Bicytopenia and pancytopenia were revealed in 9 (10.8%) and 11 (13.3%) cases, respectively. Elevated level of liver enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were detected in 29 (34.9), 37 (44.6), and 51 (61.5) patients, respectively. Conclusions: Brucellosis could affect every organ system of the human body. Variable manifestations and laboratory findings of brucellosis must be kept in mind, especially in endemic areas.