Epidemiological studies on myelodysplastic syndromes (MDS) in Middle-Eastern Europe are scarce. No data about the demographic, clinical, and laboratory features of Polish MDS patients have been published. The aim of this study was to assess the epidemiological data and toxic exposure of Polish MDS patients and their association with hematological parameters and clinical outcomes. For 15 months, 966 living MDS patients were enrolled at 24 centers (12 university and 12 community hospitals). Follow-up was conducted for the next 55 months. The percentage of patients older than 80 years (16%) was between the values for Eastern and Western countries. In patients younger than 55 years, a female predominance was observed (male/female ratio 0.70:1 vs. 1.29:1; p < 0.001). Female patients had higher platelet counts (160 × 109/l vs. 111 × 109/l; p < 0.001). Patients exposed to chemicals were younger than patients without such exposure; their median age at MDS diagnosis was 66 vs. 70 years (p = 0.037). Smokers had significantly lower hemoglobin concentrations (8.6 vs. 9.1 g/dl; p = 0.032) and lower platelet counts (99 × 109/l vs. 137 × 109/l; p < 0.001) than nonsmokers. We provide the first description of the characteristics of Polish MDS patients. Females predominated in the group aged <60 years and they had higher platelet counts. The course of the disease is affected by toxic exposure and smoking.