Background: The global prevalence of vitamin D deficiency has been studied thoroughly. Either ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) supplements treat such deficiency. However, their relative efficacy was explored in many researches. Aim: To compare the effects of vitamin D supplementation with either the enteral or parenteral formulations of cholecalciferol and ergocalciferol on raising serum 25-hydroxyvitamin D levels in children. Methods: This is a randomised controlled clinical trial that included 120 Egyptian school-aged children (5-10 years) randomly selected from the Pediatric outpatient clinic at Ain Shams University Hospitals from January 2021 to December 2022. Sequential randomization allocated the participants into 4 equal groups. Group A: received 10,000 IU of oral ergocalciferol every 4 days for 3 months, Group B: received 2400 IU of oral cholecalciferol daily for 3 months, Group C: received 200,000 IU of intramuscular ergocalciferol once, and Group D: received 200,000 IU of intramuscular cholecalciferol once. serum 25(OH)D was measured at baseline, 1,2, and 3 months after supplementation. Results: The mean ages of the recruited children were 7.40±1.33, 7.40±1.45, 8.28±2.02, and 7.23±1.65 years for groups A, B, C, and D respectively. Injectable vitamin D3 achieved the highest increments in serum 25 (OH) D after 3 months of supplementation followed by injectable vitamin D2, oral vitamin D3 and oral vitamin D2 respectively. 100% of injectable vitamin D3 recipients, 76.7 % of injectable vitamin D2 recipients, 23.3% of oral vitamin D3 recipients and 20 % of oral vitamin D2 recipients achieved sufficient vitamin D levels after 1 month of supplementation. Compliance with oral therapy was assured by asking the patients to return empty bottles. Conclusion: A loading dose of intramuscular vitamin D3 200.000 IU is the most potent, cost-effective and rapid regimen in correcting vitamin D deficiency/insufficiency in children and sustains sufficient 25 (OH) D levels up to 3 months after injection, followed by injectable vitamin D2, oral vitamin D3 and oral vitamin D2 respectively. Keywords: vitamin D deficiency, ergocalciferol, cholecalciferol, pediatrics, parenteral vitamin D2, oral D2, parenteral vitamin D3, oral vitamin D3.