In 30 patients with kidney cancer the serum concentrations of immunoglobulins IgG, IgA and IgM were determined. Blood was sampled before embolization and then before and 14, 30, 90, 180 and 360 days after nephrectomy, respectively. Statistically significant increases of IgG and IgM concentrations were found immediately after nephrectomy and were more evident later on. Only a minimal increase of IgA concentration was found. Our findings may be explained by the regression of tumour due to embolization. Persisting elevation of IgG and IgM may join the stimulation of the B-cell system by cancer antigen. Such a clinical procedure may be recommended because it may favourably influence the immunological system.