The level of circulating immune complexes (CIC) may be a reflection of the underlying malignancy and appears to be related to the stage of disease, tumor burden and prognosis. Prognostic factors at diagnosis, clinical response, survival and CIC were analyzed in 89 patients with Hodgkin's disease. All patients were newly diagnosed, in advanced stage and treated with MOPP regimen. The median follow-up was 41 months. CIC were estimated by the polyethylene glycol precipitation test. The median age was 40 years and 52% were under the age of 45. Nodular sclerosis and mixed cellularity were the most common histologies, 36 and 35% respectively. ?B? symptoms were present in 65%, bulky disease in 29% and bone marrow involvement in 4% of the total. The erythrocyte sedimentation rate (ESR) was over 30 in 72% of patients and 27% had one or two extranodal localizations. Complete remission (CR) was obtained in 69 patients (77%). The only factor influencing the CR rate was the number of extranodal localizations (p<0.05). The ten-year relapse-free survival (RFS) and overall survival (OS) were 63 and 83%, respectively. RFS was adversely influenced by lymphocyte depletion histology (p=0.009) and by performance status over 1 (p=0. 003). Elevated CIC levels were detected in 58% of the total. Patients with ESR over 30 had significantly higher values of CIC (p<0. 05). Qualitative analysis of the CIC showed high levels of positivity to immunoglobulin G and M. C-reactive protein (CRP) was identified in 42% of all samples. CRP is an acute phase protein which shows conformational similarity to the immunoglobulin molecule. There were no significant correlations between levels of CIC and the other prognostic factors. Survival was not influenced by the CIC level.