Peripheral blood lymphocytes forming E rosettes in the presence of sheep red blood cells and those bearing surface immunoglobulins (SIg) have been studied quantitatively as an evaluation of T and B lymphocytes in Hodgkin's disease. 62 patients were investigated, 21 of whom before any treatment. It appears that the lymphocytes forming E rosettes are significantly lower in percentage in 86% of the patients and in absolute count in 65%. SIg bearing lymphocytes are elevated in percentile in 61% of the cases, but the absolute count is normal in 50% of the patients and elevated in 30% only. At diagnosis the T/B lymphocytes equilibrium is modified in 13 among 21 patients but, after the initial treatment of the disease, the ratio is modified in 90% of the patients in complete remission and remains unchanged for years even in the absence of relapse or immnunosuppressive treatment. It is suggested that SIg + lymphocytes from the peripheral blood are actually B lymphocytes and not anti-T-antibody coated T lymphocytes or antigen-antibody lacking of membrane markers, which are numerous in one third of the investigated patients, might be T lymphocytes with qualitative abnormality.