This observational retrospective cross-sectional and case-controlled study measures levels of 25-hydroxy-vitamin D (25-OH-VD) in pediatric cancer survivors at different intervals and assesses the effect of 2 supplementation regimens over a period of 12 months. Sixty-eight patients were included in this quasi-experimental study, of which 32 were boys and 36 were girls. A control group of 30 healthy children were included. It was found that initial 25-OH-VD levels were insufficient (<30 ng/mL) in 61 patients (89.7%). Yet, no significant difference between the levels of 25-OH-VD in these patients as compared with the healthy control group was evidenced. However, 25-OH-VD levels were significantly higher at 18 months in patients who were supplemented with oral 50,000 IU/month vitamin D during the 12 months in comparison with patients supplemented with 1000 IU/day. Our findings indicate that pediatric cancer survivors who require frequent monitoring of their 25-OH-VD levels yielded better results when supplemented with higher doses of vitamin D over longer periods of time. A course of oral vitamin D supplementation regimen of 50,000 IU/month gave effective results with excellent compliance and no reports of any adverse or harmful effects.