Secondary school students ages is one of the most physically strong of the development stages. Besides, the girl students have menstruation. However, the axis hypothalamus - pituitary - ovarian action has been not stable in the few years, so that they have menstrual disorders. They maybe have anemia if their menstrual disorder occurs in long time of without providing adequate nutrition in time. Therefore, the assessment of red blood cell is necessary, so that the authors study this research in order to: Survey some index of red blood cell among female students in secondary school ir Thai Nguyen province. Object and Method of study: Cross-sectional descriptive study. Object study include 2 groups: group 1 are female students in urban school in Thai Nguyen city. Group 2 are female students of the secondary rural schools in Thai Nguyen. Result: Index HGB, RBC, HCT, MCV are in normal limit. Index MCH, MCHC are lower than normal limit (hypochromia).