The object of this study was to determine the efficacy and safety of glycosylated recombinant human granulocyte colony-stimulating factor (rHuG-CSF; lenograstim) after combination chemotherapy consisting of ranimustine, vindesine, melphalan and prednisolone (MCNU-VMP). One hundred thirty-nine consecutive patients with newly diagnosed multiple myeloma (MM) were allocated at random to a lenograstim group (n = 70) or a placebo group (n = 69). Patients were treated with two cycles of MCNU-VMP, and either lenograstim (2 microg/kg daily, s.c.) or placebo was administered from the day neutrophils decreased to less than 1.000/microl and was discontinued when neutrophils exceeded 5,000/microl. The median duration of neutropenia (neutrophils under 1,000/microl) was significantly shorter for the lenograstim group than the placebo group (2 days vs 9 days in the first cycle; 1 day vs 13 days in the second cycle). The incidence of febrile neutropenia in the first cycle was significantly lower in the lenograstim group than in the placebo group (9.2% vs 30.4%). No life-threatening infections were observed in either group. The two cycles of MCNU-VMP therapy were completed in 90.8% of the patients, and a higher average relative dose intensity (ARDI; 0.94) was achieved in the lenograstim group. The tumor response rate of the lenograstim group (57.8%) was higher than that of the placebo group (43.1%), but the difference was not statistically significant (chi2 = 2.634, df = 1, P = 0.105). Lenograstim was well tolerated, and no unexpected adverse events occurred. Lenograstim proved effective in controlling chemotherapy-induced neutropenia in MM patients under MCNU-VMP therapy.