Background: Iodium Deficiency Disorder (IDD) is still one of the problems in Indonesia. This disorder is often associated with anemia, which is marked by a decrease in erythrocyte counts (AE) and hemoglobin (Hb). One way to increase AE and Hb is by exercising. This study was conducted to examine the differences in AE and Hb in primary school students in IDD endemic areas. Methods: The quasi experimental study with pretest posttest group design uses 32 intervention group samples and 17 control group samples. The intervention group exercised 5x/week for 6 weeks. Subjects are children born and living in IDD endemic areas from birth, aged 6-12 years, and willing to be a research respondent. Blood samples from both groups were assessed for AE and Hb before and after exercise at Laboratory of PKU Muhammadiyah Gamping. AE and Hb was analyzed using Paired Samples T-Test for normal distributed data and Wilcoxon for abnormally distributed data. The relationship between AE and Hb was analyzed using Pearson product moment. Results: There was an increase in AE after treatment which was not significant in the intervention group (p=0.601) and control group (p=0.587). Hb were significantly increased in the intervention group (p=0.001) and not significant in the control group (p=0.071). There is a very strong relationship between the increase of AE and Hb (r = 0.798; p = 0,000). Conclusion: Exercise may increase erythrocytes counts and hemoglobin levels in primary school students in IDD endemic areas.