Gait disturbance in infants and toddlers results from various diseases, such as musculoskeletal, neuropathic, metabolic, and inherited disorders. These disorders lead to myopathies with muscle weakness. Nutritional deficiency can cause myopathy but it is very rare, because of early diagnosis and effective treatment. Vitamin D deficiency also can induce myopathy. Rickets, the clinical term of chronic vitamin D deficiency, results in secondary hyperparathyroidism that can show the characteristics of myopathy, such as muscle weakness, especially on the proximal muscles of lower extremities and the following waddling gait. We report a rare case of iatrogenic rickety myopathy. (J Korean Acad Rehab Med 2010; 34: 480-482)