We report a case of previously undiagnosed acquired immunodeficiency syndrome (AIDS) who had a mass in the post-nasal space causing almost complete nasal obstruction. Histology showed both respiratory and squamous epithelium covering an active chronic inflammatory infiltrate. Lymphoma, Kaposi's sarcoma and infiltrative fungal sinusitis were excluded. There was no evidence of the common viruses associated with lesions in AIDS. Unlike adenoid hypertrophy, the lesion was an exuberant growth with an additional chronic inflammatory reaction due to ulceration of the surface epithelium.