A retrospective review of four Gynecologic Oncology Group protocols involving aggressive chemotherapy was carried out to assess the following. Whether granulocyte determinations, which require a differential count resulting in extra cost and time, added pertinent clinical information to that obtained from the white blood cell count alone. If, there is a predictable relationship between the white blood cell count and the platelet count as a reflection of bone marrow toxicity, and whether one can predict when maximum myelosuppression will occur during a treatment program. This data revealed that the white blood count and granulocyte levels are closely related; that rarely is life-threatening thrombocytopenia noted in the absence of leukopenia; and that myelosuppression can occur during any course of treatment and is not predictable. Thus, for these treatment regimens in gynecologic malignancies, the white blood count is sufficient for monitoring toxicity and adjusting future courses of chemotherapy. Only when the white blood count is severely depressed is it necessary to monitor the granulocyte and platelet counts.