Cyclosporine (CyA) was administered to 12 patients with myelodysplastic syndrome (MDS), and a response (major erythroid response, according to International Working Group criteria) was observed in 7 patients (58.3%). The median duration of response was 18 months (range, 3-22 months). Two patients are still responding and continuing to take CyA. Three patients stopped because of malignancy complications. To identify variables associated with responsiveness to CyA therapy, we analyzed the treatments of 72 MDS patients, comprising the 12 new patients and 60 patients previously described in the literature. Responses were observed in 44 of the 72 patients (61.1%). Univariate analyses revealed that higher daily dose of CyA (P for trend test, .007) and shorter disease duration (median, 5 months versus 17.5 months, P = .04) were factors significantly associated with response. No significant associations were observed between response and bone marrow features such as erythroid hypoplasia or hypoplastic marrow. Multivariate analysis also demonstrated that high CyA dose (>5 mg/kg per day) was significantly associated with response (P = .02). The present study showed that CyA therapy is useful for MDS patients with any marrow cellularity. Shorter disease duration is a pretreatment variable correlated with response, and a higher CyA dose results in a higher response rate.