Objective: To assess the efficiency and safety of low-dose decitabine in patients with lower-risk myelodysplastic syndrome (MDS) to couple with the clinical significance of MDS-related gene mutations. Methods: This study was done in 4 institutions in Zhejiang Province. A total of 62 newly diagnosed patients with lower-risk MDS were assigned to two groups of decitabine (12 mg·m^-2·d^-1 for 5 consecutive days) and best supportive care (BSC) . Their bone marrow samples were subject to examinations of MDS-related 15 gene mutations. The primary endpoints were the proportion of patients who achieved overall response (ORR) after at least two cycles and progression-free survival (PFS) , and their relevances to the gene mutations. Results: Of 62 enrolled patients, and 51 cases were included in the final analysis. 16 of 24 patients (66.7%) in decitabine group achieved ORR versus 8 of 27 (29.6%) in BSC group (χ²=6.996, P=0.008) ; PFS prolongation of decitabine versus BSC was statistically significant (not reached vs 13.7 months, P=0.037) . Among 51 patients, at least one gene mutation was identified in 20 patients (39.2%) , including 4 single SF3B1 mutation. PFS in cases with gene mutations (not including single SF3B1 mutation) was significantly shorter than of no gene mutation (9.2 months vs 18.5 months, P=0.008) , but not for ORR (37.5% vs 58.1%, P=0.181) . Among 16 patients with mutated genes, ORR in decitabine and BSC groups were 75% (6/8) and 0 (0/8) , respectively. The most adverse events in decitabine group were grade 3 to 4 neutropenia (45.8%) and grade 3 to 4 infections (33.3%) . Conclusion This preliminary study showed that low-dose decitabine produced promising results with an acceptable safety in lower-risk MDS patients, especially for those with mutated genes. Further study targeting poor prognostic lower-risk MDS patients should be warranted.