Background: Morquio A, an autosomal recessive lysosomal storage disease, is caused by a defect in the enzyme N-acetyl-galactosamine-6-sulfatase. This leads to the accumulation of the glycosaminoglycans chondroitin-6-sulfate (C6S) and keratan sulfate (KS), resulting in various skeletal manifestations, multisystemic impairments, and significant morbidities. Objectives: This study aimed to evaluate the impact of the addition of elosulfase alfa to the hospital protocol on treating Iranian pediatricians with Morquio A syndrome. Methods: A before and after study was conducted on ten patients with Morquio A syndrome diagnosis from 2019 to 2020. Elosulfase alfa was prescribed with the standard dose of 2 mg/kg/weekly IV infusion for 54 weeks. Then, growth indices, quality of life, and cardiopulmonary data were collected by research assistants using a pre-designed check. Data were entered in SPSS version 23. Quantitative variables were compared between the two periods using the Student's t-test, and qualitative variables were compared using the χ² test or Fisher's exact test. Results: Ten pediatricians with MPS IV were included, seven of whom were female, with the mean age of 5.8±2.3 years. The mean-time for walking 6m(P = 0.005), standing (P = 0.005), the stair climb test (P = 0.007), and quality of life (P = 0.015) had significant statistical difference before and after treatment by elosulfase alfa. Conclusions: The addition of elosulfase alfa in patients with Morquio A syndrome was associated with a significant improvement outcome in the 'after' treatment period. [ABSTRACT FROM AUTHOR]