T The prevalence of iron deficiency anemia in the world is about 20-25% of the world population, especially children and women, where women of reproductive age are more likely to be exposed due to loss of blood due to the process of menstruation. Menstruation affect hemoglobin levels and iron concentrations in women of reproductive age. Because of this there should be a research to find the differences between the hemoglobin levels before and during menstruation in young adult women for the prevention or treatment of iron deficiency anemia impacts in the future. The study used a cross-sectional study design that included 31 female students from Trisakti University School of Medicine class of 2010. Data collections was by interviews regarding the age and stage of the menstrual phase information and Menorrhagia screening based on questionnaires from Cinncinati Children's Hospital Medical Center Best Evidence Statement (BEST) that is useful for screening menorrhagia with a target population of women under 25 years. Hb measurements was a assesed by hemoglobin meters by Easytouch®. Comparative analysis of the mean Hb values was performed using SPSS for Windows version 20.0 with paired t-test method and a significance level of magnitude were 0.05. The average age of the respondents was 22. 1 years; 10(32.3%) of the 31 respondents had a history of menorrhagia; the mean Hb values in the luteal phase(before menstruation) 12.4g/dL; the mean Hb values in the follicular phase(during menstruation) was 11.9g/dL. Comparative analysis of the mean values of Hb obtained both phases of the menstrual was p=0.005. There was asignificant differences of hemoglobin levels between luteal and follicular phase of menstruation in young adult women