Background: Vitamin D and calcium levels are negatively affected during postpartum period, making postnatal woman more vulnerable to health issues and consequently lowering her quality of life. Objective: This study examined the effect of aerobic exercise of moderate intensity on postpartum women's vitamin D and ionized calcium levels. Patients and Methods: A randomized controlled clinical trial was conducted on 40 postnatal women. Participants' ages ranged from 20 to 35 years old. The investigation was carried out at Al-Zahraa University Hospitals in Cairo in the Gynecology Department's Outpatient Clinic. Participants were randomly assigned into two equal groups: Control group (Group A) who did not perform any type of exercise during the study duration (n = 20), and intervention group (Group B) who were engaged in aerobic exercise program consisting of treadmill walking for 40 minutes, three times per week, for 12 weeks (n = 20). All postnatal women in both groups were evaluated by measuring serum vitamin D and ionized calcium levels before and after the treatment program. Results: Post-treatment comparison showed that Group B had a considerable advantage over Group A in terms of the mean values of vitamin D and ionized Ca++ levels (P=0.015*, P=0.003* respectively). Conclusion: Aerobic exercise is effective in increasing levels of serum vitamin D and ionized calcium in postnatal women.