Exploratory abdominal surgery in a budgerigar with a history of lethargy, feather fluffing, and melena revealed a neoplastic mass associated with the jejunal muscularis. Histologically, the nonencapsulated cellular mass was composed of sheets of spindle-shaped cells with pleomorphic nuclei, numerous and bizarre mitotic figures, and admixed anaplastic sarcomatous and giant cells. Special stains confirmed the cell of origin as the leiomyocyte. These characteristics warranted a diagnosis of jejunal leiomyosarcoma, previously unreported in the budgerigar.