Abstract Myelosuppression in myelodysplastic syndromes (MDS) is associated with the hypomethylating agent decitabine. A retrospective pooled analysis of 2 decitabine clinical trials in patients with MDS conducted Cox regression analyses of red blood cell or platelet dependence, myelosuppression, dose modification, cycle delay or dose reduction, and survival effects. In 182 patients, baseline platelet dependence was a predictor for dose modification, reduction, or delay, and death (modification: P = .006, hazard ratio [HR] = 2.04; reduction/delay: P = .011, HR = 2.00; death: P = .003, HR = 1.94). Patients with dose modifications had significantly higher overall response rates versus those with none (22% vs 10%; P = .015). Patients with no dose modifications had faster progression to AML versus patients with dose modifications (P = .004). Without dose modifications, patients tended to drop out due to disease progression or other reasons. Decitabine dose modifications on treatment may indicate response to treatment.