Recently, the cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) regimen plus rituximab (R-CHOP) have been used widely to treat patients with follicular lymphoma. We investigated a fixed scheme of combination chemotherapy protocol including CHOP, granulocyte colony stimulating factor (G-CSF) and rituximab (CHOP-GR) for patients with advanced-stage grade 1 or grade 2 follicular lymphoma in a phase II clinical trial, assessing enhancement of antibody-dependent cellular cytotoxicity of rituximab by G-CSF. Twenty-one untreated patients received two courses of CHOP chemotherapy followed by four courses of CHOP-GR, including G-CSF (s.c.) on days 11 - 14 and rituximab on day 15. Overall response rate was 76% (16 of 21 patients). Two patients, one with no response and subsequent allogeneic hematopoietic stem cell transplantation and one with progressive disease, died of lymphoma. One patient refused to continue therapy, whereas two were rediagnosed and no longer met histologic criteria; these three patients were classified as nonresponders. After a median observation time of 23 months, the 19 histologically assessable patients showed a 2-year progression-free survival rate of 82%, whereas 2-year overall survival was 95%. Fifteen patients (79%) continued in remission during this median follow-up period. Of seven patients with initial bulky mass, five responded to therapy. The most frequent adverse events were leukocytopenia (100%) and neutropenia (100%), followed in turn by alopetia (94%) and nausea/vomiting (79%). Of 11 patients examined for bcl-2 translocation in peripheral blood or marrow by polymerase chain reaction (PCR), four were positive, whereas three of the four had complete remissions and converted to PCR negativity after therapy. According to short-term observation, CHOP-GR is a safe and effective therapy for patients with advanced-stage follicular lymphoma.