Inflammatory lesions and cysts are by far the most common causes of swelling or enlargement of Bartholin's glands, and carcinomas, though rare, are the most frequent solid lesions that arise at this site. There have been very few reports of benign solid lesions of Bartholin's gland, and, among these lesions, the distinction between adenoma (AD) and hyperplasia has not been well defined. All cases diagnosed as either Bartholin's gland adenoma or hyperplasia in the Armed Forces Institute of Pathology files were reviewed. Using specific criteria, 17 qualified as nodular hyperplasia (NH), 1 as AD, and 1 as adenomyoma (AM). Five NHs, the AD, and the AM were studied with immunohistochemical stains for estrogen receptor (ER), progesterone receptor (PR), MIB-1, and p53. The average age of the patients with NH was 35 years (range, 19 to 56). These lesions were solid or solid and cystic, had a mean maximal dimension of 2.3 cm, and were frequently thought to be Bartholin's cysts on clinical examination. Microscopically, the NHs had an irregular or lobulated contour and were composed of a proliferation of cytologically bland mucinous acini with maintenance of the normal duct-to-acinar relationship. Varying degrees of inflammation and squamous metaplasia of the ducts were common in NH. The patient with the AD was 45 years old and the patient with AM was 65. Both were well-circumscribed, solid lesions, 2.2 and 2.5 cm in maximal dimension, respectively, and composed of a haphazard proliferation of acini and tubules. A small adenoid cystic carcinoma (ACC) arose from the periphery of the AD. p53 positivity was evident in up to 40% of the ACC cells; the cells in the adjacent AD were negative for p53. Only occasional cells were MIB-1 positive (<5%) in some cases, and ER and PR were absent in the epithelial elements in all 7 cases tested but were focally present in the stromal cells of 3 of the 5 NHs and the fibromuscular stroma of the AM. The patient with the AM and the one with the AD are alive without evidence of recurrent or metastatic disease after 4 months and 19.8 years, respectively. NH, AD, and AM of the Bartholin's gland, as defined in this study, are extremely rare lesions. NH occurs in younger patients and is often associated with inflammation or obstruction of Bartholin's duct.