It has been suggested that altered interleukin (IL) regulation may be involved in the pathogenesis of schizophrenia. In this cross-sectional, case-controlled study, patients with schizophrenia and a control group of healthy subjects, matched by age, sex and body mass index, were evaluated. The levels of IL-1 alpha and IL-2 in blood serum were measured by enzyme-linked immunosorbent assay. The fasting serum IL-2 levels were significantly higher in patients with schizophrenia compared with the control subjects, but there was no difference between the fasting serum levels of IL-1 alpha in patients with schizophrenia and the control subjects. Our results suggest that patients with schizophrenia have altered IL-2, but not IL-1 alpha, regulation.