Myelodysplastic syndrome (MDS) with isolated deletion 11q is a rare favorable cytogenetic abnormality with a low risk of progression to acute myeloid leukemia (AML). The aim of this study is to describe the clinical characteristics and long-term outcomes of patients with isolated del(11q) MDS. Between August 1997 and January 2024, 52 patients with MDS and isolated del(11q) were diagnosed, representing 0.4 % of the cohort. The median age was 69 years, with a mild male predominance (62 %). By the World Health Organization (WHO) 2022, 42 % of patients had MDS with low blasts. With a median follow-up of 96 months, the median survival was 71 months with a 5-year survival rate of 53 %. The 5-year survival rates were 45 % and 68 % in the hypomethylating agents and best supportive care group, respectively (P = 0.63). Multivariate Cox regression analyses identified age, absolute neutrophil count, hemoglobin, and blast percentages as significant prognostic factors. Despite isolated del(11q) MDS being classified as a very-good-risk cytogenetic abnormality, long-term survival is poor with the risk of progression to AML and complications from cytopenias. The poor long-term survival indicates the need for the investigation of effective supportive care and early intervention to benefit patients with lower-risk MDS and high-risk features.