It has been claimed that inhalational anesthetics affect many phases of immune response. Although, there are a lot of studies on the effects of widely used anaesthetic agents and methods on the immune system, there are only a few studies to show the effects by evaluation of neopterin concentrations as an important marker of cellular immunity. This study was done to evaluate possible effects of inhalation anesthetics, such as desflurane, isoflurane, and sevoflurane on the immune system by measuring urinary neopterin concentrations in patients who underwent laparoscopic cholecystectomy. The study is randomized, prospective and double blind. Urinary neopterin was measured in patients submitted to general anesthesia with either desflurane (n = 20) or isoflurane (n = 11), or sevoflurane ( n = 13) in laparoscopic cholecystectomy. Urine samples were collected preoperatively, at 2(nd) and 24(th) hours post-operatively and the neopterin per creatinine concentrations were measured by using high-performance liquid chromatography.