Objectives: Since metformin was reported to decrease overall cancer incidence and mortality and to have antiproliferative and antiinvasive properties, we investigated the impact of metformin intake on survival in endometrial cancer patients. Material and methods: Medical records and survival data of 126 patients with endometrial cancer were analyzed retrospectively. U Mann-Whitney and chi-square tests were applied to compare clinicopathological features. Kaplan Meier model with log-rank test was used to compare survival in the subgroups. Cox proportional hazard model was applied to analyze the relationships between particular factors and overall survival. Results: 107 patients met study criteria and were divided into three groups: 1) patients with type 2 diabetes and metformin users (n=30), 2) patients with type 2 diabetes and metformin non-users (n=38), 3) patients without diabetes mellitus (n=39). No difference in survival between metformin users versus metformin non-users (p=0,86) was observed. Metformin intake, diabetes mellitus co morbidity, plasma glucose level and BMI appeared without influence on survival. When the analysis was restricted to the subgroup of type I endometrial cancer or to endometroid histological type, still neither metformin intake nor diabetes influenced the prognosis. Conclusions: Metformin intake does not alter overall survival in endometrial cancer patients. Diabetes mellitus has no influence on survival in endometrial cancer patients.