Tumor necrosis factor α (TNFα) and leptin concentrations were determined in the abdominal subcutaneous and visceral (omental) adipose tissue of patients undergoing elective open-abdominal surgery and compared with their body mass index. The concentration of leptin did not differ significantly between women and men, being high in subcutaneous fat tissue and low in visceral fat tissue. TNFα concentration in subcutaneous fat tissue was approximately the same in both genders, but it was significantly lower in visceral fat tissue of women and unchanged in visceral fat tissue of men. A significant correlation between BMI and leptin was found in the two fat tissue compartments of both genders, but the correlation between BMI and TNFα was found only in subcutaneous fat tissue of women.