A 2-kg, 11-year-old neutered male rabbit (Oryctolagus cuniculus) was presented for examination of a mandibular swelling. On clinical examination, 2 well-defined subcutaneous masses (15 mm and 5 mm in diameter) were identified along the ventral area of the left horizontal minus of the mandible. An intraoral examination revealed a moderately elongated first premolar located within the left mandibular arcade. The mandibular masses were removed through surgical excision and coronal reduction was performed on the first left lower premolar. The 2 masses were isolated from the underlying tissue and there was no evidence of involvement of the abnormal tissue with structures comprising the oral cavity. The histological examination of the excised tissue revealed unencapsulated cystic, multiloculated and multilobulated masses consisting of numerous, variably sized cystic spaces and tubules supported by a moderately dense fibrovascular stroma. The final disease diagnosis of the mandibular tissue masses was cystic apocrine gland adenomatous hyperplasia, most likely of sweat gland origin. Apocrine gland hyperplasia is a benign, nonneoplastic lesion. The etiology of cystic hyperplasia of the apocrine glands is unknown in domestic species, but it is reported to occur in male dogs and less frequently in cats. This case is believed to be the first description of apocrine gland hyperplasia in the submandibular region of a rabbit Copyright 2011 Elsevier Inc. All rights reserved.