Hypothyroidism is a common endocrine disorder resulting from the inability of the thyroid gland to produce sufficient thyroid hormone for the metabolic demands of the body. Clinical symptoms and signs are often non-specific and subtle. Muscular symptoms are frequently reported. Rhabdomyolysis is a life-threatening condition caused by necrosis of muscles and leakage of toxic intracellular components into the blood circulation. Hypothyroidism induced rhabdomyolysis, represents an unusual clinical occurrence. This is a case of a middle-aged man, who presented with severe myalgias, following an intramuscular injection. After laboratory work-up, he was diagnosed with rhabdomyolysis. Laboratory and ultrasound tests disclosed primary hypothyroidism of auto-immune etiology.