The levels of soluble interleukin-2 receptors (sIL-2R), beta-2 microglobulin (beta-2M), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured in the serum of 50 previously untreated patients with non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL) as well as in 25 age and sex-matched normal controls. Compared to normal controls, mean serum levels of sIL-2R and beta-2M were significantly increased in both NHL and CLL (p < 0.001) while the increase in ESR and CRP was less marked (p < 0.01 and p < 0.05, respectively). Comparison of these tumor markers with histologic grading showed statistically significant differences only for CRP between low, intermediate and high-grade lymphomas (p < 0.001 and p < 0.05). More advanced stages exhibited higher mean values of all serum markers than early stages (p < 0.001 for sIL-2R, beta-2M and ESR and p < 0.05 for CRP). An association with the presence of b-symptoms was observed only for sIL-2R (p < 0.05). In addition, sIL-2R as well as beta-2M were able to predict time to progression in patients with diffuse large-cell lymphomas. We conclude that of the four tumor markers tested sIL-2R and beta-2M more frequently showed increased serum levels and were associated with clinical stage and/or presence of b-symptoms. Both sIL-2R and beta-2M were also found to have prognostic significance for survival.