The effects of granulocyte-colony stimulating factor (G-CSF) have been studied in several clinical settings. G-CSFs are widely used to stimulate the production of granulocytes and are well known to mobilize peripheral blood stem cells (PBSCs). However, very few studies have examined differences among G-CSFs. The aim of this study was to compare the mobilization of PBSCs induced by a standard dose of two G-CSFs following biweekly cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) therapy. Using a standard dose of G-CSF, we conducted a randomized, crossover trial that compared the efficacy of two kinds of G-CSF, glycosylated [lenograstim (2 micrograms/kg)] and mutated [nartograstim (1 microgram/kg)], on PBSC mobilization in 10 patients with non-Hodgkin's lymphoma after biweekly CHOP chemotherapy. Lenograstim (2 micrograms/kg) was more effective in shortening the duration of neutropenia than nartograstim (1 microgram/kg) (3.8 days vs. 5.0 days, p < 0.05, the number of days for the neutrophil count to reach 5 x 10(9)/l from nadir). The number of CD34+ cells and granulocyte-macrophage colony forming units (GM-CFU) was higher for lenograstim but no statistically significant difference between the two groups was found. Glycosylated G-CSF is more effective than mutated G-CSF in shortening the duration of neutropenia. As for the mobilization of CD34+ cells and the number of CFU-GM, there was a tendency to increase in the lenograstim group but no statistically significant differences were found.