A total of 32 patients (25 with advanced MDS and 7 with t-AML) were enrolled in this study to evaluate the efficacy and toxicity of the low-dose cytarabine and homoharringtonine in combination with granulocyte colony-stimulating factor (G-CSF) (CHG protocol) in patients with advanced myelodysplastic syndromes (MDS) or MDS-transformed acute myeloid leukemia (t-AML). All the patients were administered the CHG regimen comprising low-dose cytarabine (25 mg/day, intravenous continuous infusion, days 1-14), homoharringtonine (1 mg/day, intravenous continuous infusion, days 1-14), and G-CSF (300 microg/day, subcutaneous injection, days 0-14, interrupted when the peripheral white blood cell count reached >20 x 10(9)/L). The overall response rate was 71.9% after the administration of one course of the CHG regimen. Of the 32 patients, 15 (46.9%) achieved complete remission (CR) and 8 (25%) achieved partial remission (PR). This regimen was followed by a post-remission therapy that included conventional chemotherapy, when CR was achieved. Of the patients with CR who just received post-remission regimens as homoharringtonine and cytarabine (HA) and daunorubicin and cytarabine (DA) 6 relapsed rapidly and just had a mean 6.1 months of CR. Otherwise, the other 8 out of 14 patients with CR alternatively received subsequent chemotherapy, which combined mitoxantrone, idarubicin, pirarubicin, or aclarubicin with cytarabine. The mean CR duration of the 8 patients had reached 10.6 months, and 5 of the 8 still kept a continuous CR. The median overall survival (OS) was 18.2 months. There were no statistically significant differences for CR, PR, and OS when the patients were grouped by age, blasts in bone marrow, and karyotypes, respectively. No treatment-related deaths were observed. Myelosuppression was mild to moderate, and no severe non-hematological toxicity was observed. Thus, a CHG priming regimen as an induction therapy was well tolerated and effective in patients with advanced MDS or t-AML. Stronger and alternative subsequent chemotherapy is necessary for patients with CR to maintain longer CR and better OS.