BACKGROUND We report a case of acute steroid myopathy in a patient with eczema receiving one dose of intra-muscular injection of Compound betamethasone. METHODS Acute steroid myopathy (ASM) is usually caused by exogenous corticosteroids, and typically, occurs with therapy using intravenous corticosteroids at high doses. METHODS The patient was considered as a diagnosis of acute steroid myopathy. METHODS The patient was treated with non-steroid anti-inflammatory drug and other symptomatic therapy. RESULTS ASM was gradually improved after 2 weeks symptomatic treatment and completely recovered after one-month treatment. CONCLUSIONS The diagnosis of steroid myopathy is a clinical diagnosis based on characteristic symptoms. Higher dose of steroids, especially fluorinated steroids, for longer periods of time increases the risk of steroid-induced myopathy.