Hydatid disease is a cyclo-zoonotic parasitic infection mainly affecting liver and lung. Primary hydatid cyst in the muscle is very rare and is usually secondary, resulting either from the spread of cysts spontaneously or after surgery. Here, we report a case of primary hydatid cyst within brachialis muscle, with emphasis on the fact that it should be included in the differential diagnosis of peripheral cystic mass to avoid invasive investigations like FNAC. It results in better patient management because leakage of the cyst contents may not only result in recurrence and dissemination, but may also cause anaphylaxis and subsequent surgical resection difficult.