A prospective study of serum cytokine levels was performed in patients randomly assigned to undergo either laparoscopic cholecystectomy (LC) or open cholecystectomy (OC). The kinetics of serum interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), and cortisol were studied in both groups of patients. Cytokine and cortisol levels were measured in serum samples from patients who underwent either LC (n = 14) or OC (n = 14) using enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Serum samples were obtained 24 h before surgery and 24 h and 7 days after surgery. IL-6 levels differed significantly (p < 0.05) between the LC and OC groups. IL-1 beta, IL-10, TNF-alpha and cortisol levels showed no significant differences (p > 0.05). Kinetic studies of IL-6, IL-1 beta and TNF-alpha levels revealed them to behave similarly, 24 h after surgery the levels of these cytokines were higher than those 24 h before surgery. These levels normalized by 7 days after surgery. Cytokine concentrations were always higher in the OC group than in the LC group. IL-1 beta and IL-10 levels were the most stable in both groups, though cortisol levels were also fairly stable.