Background: 20% of cases of endometrial hyperplasia without atypia is progressed as atypical hyperplasia and in 5% of cases-is progressed as endometrial cancer.Recent studies are focused on the effect of pro-and anti-inflammatory cytokines to the pathogenesis of EH.That's why,our attention was drawn to frequency of 25(OH)vitaminD deficiency with patients and anti-inflammatory and anti-peroxidation effects of above cited vitamin,which affects to the production of pro-inflammatory cytokines and impacts by the optimizing metabolic status.These factors were taken into consideration and we aimed to study the impact of vitaminD3 supplements in both-clinical outcomes and metabolic profile to the women with EH. Methods: We have selected 32 patients (25.9+/-10.1years of age) with diagnosed simple EH,whose serum 25(OH)D3 levels varied from 20.1+/-10.1ng/ml. BMI was ranged between (30.1 +/-10.5kg/M2).The randomization of patients conducted randomly by two groups: study group(n=17),in which patients were given 50.000IU dose of vitaminD3 weekly during 16 week and placebo group(n=15).We were determining the level of 25(OH) vitaminD in the blood serum and we were diagnosing EH by TVS control,which was later confirmed with the result of endometrial pipelle biopsy.After the end of treatment we made again TVS to evaluate the results.The research was conducted in the late proliferative phase of the menstrual cycle at the both stages. Results: After 16week, unlike a placebo group,the study group patients had increased serum 25(OH)vitaminD levels (+11.0±10.6vs.+1.9 ± 8.1ng/mL,p < 0.001).Herewith,in 14(82%)of the patients of research group had reduced thickness of endometrium(-3.0±1.5mm.p < 0.001),in 3(18%) of patients the indicator of previous treatment was maintained unlike the placebo group,where in the 11(73%) of patients had the increase of thickness of endometrium (+2.0±1,5mm.p < 0.001) and it became necessary to do repetitive biopsy and then other types of intervention,in accordance with the results.The results in 4(27%) of patients were not changed. Conclusions: Use of the supplements of vitamin D3 had the positive effects in women diagnosed with EH and vitaminD3 deficiency.Due to the results of the study,we are able to say that vitamin D3 plays a role in decreasing the complications associated with EH.In addition,we could conclude that a new approach of using vitaminD3 requires further observations and clinical researches,what may change the policy of the treatment of EH.