After approved by the Ethical Committee and signed informed consent, 40 patients aged from 18 until 60 years undergoing nephrectomy will be randomized in two groups. Group 1 patients will receive a single dose of 300 mg pregabalin, 1 hour before the surgical incision; group 2 patients will receive a placebo dose. Pain intensity will be assessed with the numeric rating scale. The consumption of tramadol in 24 hours after surgery and the time for the first complementation dose will be registered. Blood samples will be collected by 6 hours and 24 hours after surgical incision, for IL-6 dosage, and maintained at -70 celsus degree. The IL-6 dosages will be performed by the ELISA (enzyme-linked immunosorbent assay) method. The number of patients was calculated by Instat Graph® program. To detect difference in pain intensity of 3 between the groups by NRS, with 95% of power (estimated SD= 2.0), when the alpha level is set at 0.05, the sample should be of 20. Statistical analyses will be performed with parametric and nonparametric tests, considering the variety studied. The statistical program that will be utilized is Instat Graph®.