Clinical trials were carried out of the protective action of dicarbamin in 33 patients with Hodgkin's disease (13 males and 20 females, average age--31 years). They received standard chemotherapy ABVD (doxorubicin--25 mg/m2, bleomycin--10 mg/m2, vinblastine--6 mg/m2, dacarbazine--375 mg/m2, intravenously, on days 1 and 15 of each cycle, every 4 weeks. Patients suffering neutropenia after the first injection of the cytostatic drugs were given dicarbamin 100 mg/day on day 5 before a second administration. Treatment with dicarbamin continued for 15 days. Its protective effect was reported in 27 patients (81.8%). Leukocyte and granulocyte count before dicarbamin was 3.74 +/- 0.25 x 10(9)/l and 1.42 +/- 0.17 x 10(9)/l, respectively. On completion of the polychemotherapeutic cycle, the indices rose to 5.0 +/- 0.28 x 10(9)/13 and 2.49 +/- 0.25 x 10(9)/l, respectively. The beneficial effect of dicarbamin was also demonstrated by a quick recovery of leukocyte levels than in controls (p > 0.5). After the next cycle of polychemotherapy (ABVD) plus dicarbamin was given for Hodgkin's disease and grade III-IV leuko- and granulocytopenia, leukocyte and granulocyte concentrations returned back to normal which indicated the protective action of dicarbamin.