Rickets due to vitamin D deficiency, typically presenting as bowed legs in toddlers, is uncommon in the modern era. We describe the case of a nine-year-old girl with autism and developmental delay who was evaluated for chronic intermittent extremity pain for more than one year prior to referral to the emergency department for hypocalcemia and increased alkaline phosphatase, which eventually led to the diagnosis of rickets confirmed by radiographic and laboratory findings. This report highlights the importance of the patient's history of developmental delay and autism in the evaluation and approach to limb pain, and discusses the appropriate diagnostic approach.