BACKGROUND: Heavy menstrual bleeding is one among the factors that cause significant morbidity to women due to anemia and also significantly affects the women‘s quality of life. The prevalence rate of heavy menstrual bleeding varies between developed and developing countries. But there is lack of information about heavy menstrual bleeding in Tanzania and hence there is need of effort to look for prevalence of heavy menstrual bleeding and factors that associate with it. OBJECTIVES: To determine the prevalence of heavy menstrual bleeding and the factors that associated with heavy menstrual bleeding among women attending obstetrics and gynecology clinic of KCMC in the year 2015. METHODOLOGY: This was a cross sectional study conducted in Obstetrics and gynecology clinic of KCMC. The study population was women who attended obstetrics and gynecology clinic of KCMC in the year 2015. Data was extracted from patient files and filled in the data collection forms. Data was entered and analyzed by using SPSS version 20. RESULTS: Out of 300 patients files only 162(54%) was found to have complete and legible data to be extracted. The patients’ age ranged 15-59 years with mean age of 37.6(SD + 9.98) years. The prevalence of heavy menstrual bleeding was 9.9% due to longer menstrual period of more than 8 days and 24.1% due to either uses of more than 5 wet sanitary pads or self-reported to have heavy menstrual period. Low hemoglobin level, presence of uterine fibroid, use of hormonal contraception and presence of clots on menstrual blood was found to be associated with heavy menstrual bleeding. CONCLUSION: The prevalence of heavy menstrual bleeding was found to be relatively similar to one reported by WHO studies in developing countries. Community based research concerning perception and knowledge of heavy menstrual bleeding are required as this will help in giving the reason of marked difference on prevalence between developing and developed world.