Proinflammatory cytokines, such as tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6), act as mediators of post-injury inflammation and increase pain sensitivity. Pentoxifylline (PTX) has the property of inhibiting TNF-alpha, IL-1, and IL-6 production. Previous studies revealed that the pre-injury or preoperative administration of PTX inhibited consequent hyperalgesia or postoperative pain. The aim of the study was to determine, if postoperative PTX administration affects postoperative pain. A group of 40 patients undergoing laparotomic cholecystectomy received postoperatively PTX at 10 mg/kg or placebo directly after the termination of general anesthesia. There were no differences in postoperative pain, analgesic drug requirement or TNF-alpha and IL-6 serum levels between the groups.