An aneurysmal bone cyst (ABC) is a benign lesion that often arises eccentrically from the metaphysis of long bones and which can expand bone tissue as it grows. It is a rare lesion, frequently appearing in the long bones of the lower limb. Localizations on the hands and feet are rarer and often limited to tubular bones.We report the case of a 2-years-old girl initially admitted for a hard dorsal immobile and slightly painful swelling of the 5th metacarpal of the left hand, which didnt limit the metacarpo-phalyngeal joint mobility and which was evolving since 4 months. The standard hand x ray and CT-Scan showed a central lytic multiseptatedmetaphyseal-diaphyseal lesion, with a well-defined appearance, expansile but without extending beyond the cortices. The biopsy confirmed the diagnosis of an aneurysmal cyst that was surgically curetted then auto-grafted.A follow-up of 1 year showed a filling of the cystic cavity and bone remodeling which resulted in an almost normal clinical appearance of the patients hand.A metacarpal location of an ABC is rare. The performance of a biopsy is fundamental to confirm the diagnosis before that any treatment is undertaken.