In brief: This study compared three stages of iron deficiency (iron depletion, iron deficiency erythropoiesis, and iron deficiency anemia) in athletes and controls immediately after menstruation and at midcycle. All athletes had subnormal serum ferritin levels at both test periods, indicating stage 1 iron deficiency. The control group's serum ferritin levels were normal. Two athletes were stage 2 iron deficient, but no athletes or control subjects were in the third stage of iron deficiency. This study shows that stage 1 and 2 iron deficiency may exist in female athletes even in the absence of anemia. Therefore, sports programs should provide nutrition counseling, but indiscriminate use of oral iron supplements should be discouraged.