Xerostomia is common among patients with advanced cancer and is likely to contribute to oral disease. This study determined the prevalence of oral signs and symptoms among a group of 70 terminally ill cancer patients [25 male, 45 female; age range 42-88 (mean 66) years] complaining of oral dryness, and examined the associated oral microflora. Imprint cultures for yeasts, coliforms and staphylococci were collected from the tongue and, in denture wearers, from the plate and denture fitting surface. A swab was collected for culture of herpes simplex virus. 68 patients (97%) complained of oral dryness during the day and 59 patients (84%) complained of oral dryness at night. Oral soreness was reported by 22 patients (31%). 46 patients (66%) had difficulty talking and 36 (51%) reported difficulty eating. Of the 56 denture wearers, 40% complained of denture problems. On examination, 63 (90%) of the patients had clinically dry mouths. Oral mucosal abnormalities were detected in 45 patients (65%), most commonly erythema (20%), coated tongue (20%), atrophic glossitis (17%), angular cheilitis (11%) and pseudomembraneous candidosis (9%). 47 (67%) of the patients carried yeasts, 18 (26%) were carriers of Staphylococcus aureus and 13 (19%) carried coliforms. Herpes simplex virus was isolated from 5 patients, of whom 2 had herpetic stomatitis. Oral complications and abnormalities of the oral microflora can be detected among significant numbers of terminally ill cancer patients with xerostomia.