Background: Cow's milk allergy (CMA) is the predominant food allergy among babies, with an estimated frequency in developed nations between 0.5 percent and three percent. Aim: This research aimed to evaluate the vitamin D level and nutritional status in babies with cow milk protein allergy before and after treatment. Patients and methods: This observational study has been performed on a total of 30 infants diagnosed with cow's milk protein allergy (CMPA) and 40 healthy control infants to assess the nutritional status and vitamin D levels in infants diagnosed with CMPA before and after treatment. Results: An insignificant variation has been observed among groups regarding family history of allergy, anthropometric assessment, maternal vitamin D supplementation throughout pregnancy, and EBF time p>0.05. Nonetheless, significant variation has been observed in antibiotic usage in the first triTrimester of life (p < 0.05). Insignificant variations have been discovered in total energy, carbohydrates, proteins, lipids, calcium, 25(OH)D, and phosphate levels (p>0.05). Conclusion: We found insignificant variances among groups in age, sex, gestational age, allergy history, anthropometric assessment, vitamin D supplementation, exclusive breastfeeding time, total energy, carbohydrate, protein, lipids, and calcium levels. However, significant differences were found in delivery type, antibiotic use during the first Trimester, and 25(OH)D and phosphate levels.