Neutropenic pediatric patients with solid tumors and malignant lymphomas were treated with recombinant granulocyte-macrophage colony stimulating factor (rh-GM-CSF). Eleven patients, including seven lympho-reticular malignancies, two Ewing's sarcoma and one patient in each group with the diagnosis of nasopharyngeal rhabdomyosarcoma, malignant mesenchymal tumor, entered the study. Six were females and five were males, the mean age was 10.4 yr, the range was 4 to 21 years. rh-GM-CSF was given at the dose of 5 micrograms/kg s.c. daily, starting either on the day following the last day of cytotoxic chemotherapy or when ANC < 1000/ml was determined. All patients received rh-GM-CSF for a total of seven days. Hematopoietic recovery occurred in all children except one. The response to rh-GM-CSF was achieved in a mean time of 7.4 days. Tolerance to rh-GM-CSF treatment was good. Adverse events were documented as fever, nausea, vomiting, fatigue, chills and itching. Sagittal sinus thrombosis developed in one patient 5 days following the completion of chemotherapy and rh-GM-CSF cycle. In conclusion, rh-GM-CSF can be applied during the intensive chemotherapy schedules of pediatric cancer patients.