Vancomycin is a glycopeptide antibiotic which is commonly used to treat methicillin-resistant staphylococcal infections. It is commonly used in pediatric oncology wards for children with febrile neutropenia. We report a very rare side effect of vancomycin induced myopathy in a child with acute lymphoblastic leukemia. To the best of our knowledge, this is the first case reported from Oman.