We have studied the effect of recombinant human granulocyte colony-stimulating factor (G-CSF) on the growth of three different human neuroblastoma (NB) cell lines, using a clonal cell culture and a short proliferation test. The results have shown a lack of effect of G-CSF on the three cell lines. These data promote the use, in clinical trials, of G-CSF as adjunctive treatment in children with NB receiving intensive chemotherapy.