Little is known about quality of care for patients with myelodysplastic syndromes (MDS), or patient and provider factors that influence quality. We identified Medicare enrollees diagnosed with MDS between 2006 and 2011, and analysed linked claims for performance on two widely-accepted quality measures: diagnostic bone marrow cytogenetic testing (diagnostic quality) and pre-treatment iron assessment for patients receiving an erythropoiesis-stimulating agent (ESA; treatment quality). A total of 4575 patients met the criteria for diagnostic quality measurement, and 3379 for treatment quality measurement. In the diagnostic cohort, 74% had a claim for marrow cytogenetic testing 3 months before to 3 months after diagnosis. In multivariate models, younger age (P < 0·001), treatment at a higher-volume MDS centre (P < 0·001), and claims for pancytopenia (P < 0·001) were all associated with higher levels of testing. A borderline result was observed for diagnostic year, with improvement over time (P = 0·06). In the treatment cohort, 56% had evidence of pre-ESA iron assessment, with higher rates for later years of diagnosis (P < 0·001), higher household income (P = 0·03), and those treated at higher-volume centres (P = 0·01). In this large cohort of patients with MDS, quality of care was suboptimal overall, but worse in several specific subgroups. These data suggest that targeted educational and/or process-focused interventions are warranted.