The aim of this study was to analyze the changes in fibrinogen concentration in patients who underwent total hip arthroplasty. In this prospective study 30 patients (18 females) with a mean age of 70 years (range, 45–86 years) suffering from idiopathic hip osteoarthritis and qualified for elective surgery were analyzed. Fibrinogen levels were established immunoenzymatically prior to the surgery, 6 hours after the procedure, and on days 2, 4 and 6 after the surgery. None of the patients demonstrated any symptoms of venous thromboembolism during hospital stay. The mean fibrinogen concentration equaled 366 mg/dl before the surgery, dropped to 311 mg/dl 6 hours after the procedure, then increased up to 827 mg/dl on POD 4. Increased baseline fibrinogen values (>400 mg/dl) were found in 20% of patients. After elective total hip arthroplasty, fibrinogen acts like an acute phase protein.