This study was intended to ascertain whether the adjunctive administration of filgrastim (r metHuG-CSF, Amgen) would influence the dose intensity of chemotherapy or the morbidity of myelosuppression in patients receiving MOPP or MOPP/EVAP hybrid chemotherapy for Hodgkin's disease. In a prospective randomized trial, two regimens for the treatment of Hodgkin's disease were compared. The substudy described here randomized patients receiving either regimen to receive filgrastim on the days when chemotherapy was not administered. During chemotherapy, parameters of myelosuppression were documented, including dose delays, the severity and duration of neutrophil and platelet nadirs, infective episodes, and resulting hospital admissions. In the MOPP arm, 13/25 eligible patients, and, in the MOPP/EVAP arm, 12/22 eligible patients, received filgrastim. The use of filgrastim made no statistically significant difference to the administered dose intensity for either MOPP (P = 0.57, 95% confidence interval (CI) 15-point increase to 8-point reduction) or MOPP/EVAP (P = 0.53; 95% CI 7-point increase to 11-point reduction). In patients receiving MOPP, filgrastim reduced the median duration of leucopenia (P = 0.007) and the severity of the white blood cell nadir (P = 0.036); however, no statistically significant effect (at the 5% level) was seen in platelet or haemoglobin nadirs, the number of days of in-patient hospitalization, the number of admissions for infective complications, the incidence, grade or duration of infections, or the incidence of febrile neutropenia. In patients receiving MOPP/EVAP, filgrastim had no significant effect on the duration or depth of leucopenia but was associated with a reduction in the median haemoglobin (P = 0.002) and platelet nadirs (P = 0.015). No effect on the above listed sequelae of myelosuppression was influenced by the administration of filgrastim. This study, although small, suggests that the routine use of filgrastim, aimed at influencing the administered dose intensity of conventional dose chemotherapy in Hodgkin's disease, is not warranted.