Cytokines play important roles in the pathogenesis of lymphomas. The aim of this study was to determine the relations between serum levels of interleukin-2 (IL-2), IL-6, and IL-10 and parameters of International Prognostic Index (IPI). Serum levels of IL-2, IL-6 and IL- 10 were measured using a sensitive enzyme-linked immunosorbent assay in the pretreatment frozen sera from 43 patients with non-Hodgkin's lymphoma. The patients we included in the study were divided into two groups, one with high risk and the other with low risk according to the IPI in regard to their ages, stages, performance status, extranodal involvements, and serum levels of lactate dehydrogenase. In the high-risk group, serum levels of IL-2 (0.852 +/- 0.268 ng/ml), IL-6 (0.461 +/- 0.206 ng/ml), and IL-10 (0.816 +/- 0.240 ng/ml) were found to be higher than serum levels of IL-2 (0.667 +/- 0.170 ng/ml), IL-6 (0.355 +/- 0.075 ng/ml), and IL- 10 (0.643+0.177 ng/ml) in the low-risk group (p < 0.05). There was a correlation between the patients with high risk according to the IPI criteria and high levels of serum cytokines (IL-2, IL-6, IL-10). Knowledge of the serum levels of these cytokines in patients with newly diagnosed aggressive non-Hodgkin's lymphoma may help us to have some information about the possible prognosis, the activation of disease, and to decide on appropriate therapeutic approaches for individual patients.