['Serum prostate-specific antigen (PSA) level is a widely used serum marker for diagnosis and management of prostate cancer. Although not well-defined, liver appears to be the most likely site of PSA metabolism. However, general anaesthesia usually changes hepatic blood flow, therefore it may affect the metabolism of PSA. In this study we investigated the affect of general anaesthesia on the serum total PSA, free PSA and free to total PSA levels.', '30 male patients who were hospitalised in the internal medicine clinic (non-surgery group) and 30 male patients who would undergo operation under general anaesthesia (15 for cholecystectomy and 15 for inguinal hernia repair) enrolled into the study. PSA measurement was done on the day of the hospitalisation (which was also the day of operation for surgery group), on the 24th hour following the first measurement and on the 21st day. Anaesthesia was standardized for all patients.', 'There was no statistically significant difference in serum total PSA (p >0.05), free PSA levels (p >0.05) and free to total PSA ratio (p >0.05) between the surgery and non-surgery groups. There were statistically significant decreases in the 24th hour total PSA levels (13.8% in surgery group, p <0.05, and 13.1% in non-surgery group, p <0.05) and in the free PSA levels (4.0% in surgery group, p <0.05, and 8.2% in non-surgery group, p <0.05). There was no statistically significant difference in the free to total PSA ratios (p >0.05 and p >0.05, respectively).'] Does general anesthesia affect the serum complexed and free prostate specific antigen levels?