Parotid flow rate and chemistry of 78 HIV + gay/bisexual men and 27 HIV-gay/bisexual controls were compared on a longitudinal basis at 4-month intervals over a 1 yr period for changes indicative of inflammatory or autoimmune diseases of the salivary glands, or reduced protective capacity toward oral opportunistic infection. Parotid saliva was examined for concentrations of sodium, chloride, phosphate, total protein, lysozyme, lactoferrin, secretory IgA, salivary peroxidase, histatin and albumin. Chloride, lysozyme and peroxidase were significantly higher in HIV + at all 3 examinations and increased in concentration over time. Although mean values for stimulated flow rate were not significantly different in the two groups over the year, there was a significant increase in the number of HIV + with reduced flow over time. In 6% of HIV + there was a marked reduction in flow rate and Sjögren's syndrome-like elevations in parotid chemistry but no enlargement. At all examinations low flow rate was significantly related to oral candidiasis; T4 levels were inversely related to oral candidiasis, but not to concentration of salivary components or flow rate; nor was AZT use. As a group the HIV + patients maintained normal flow rate and secreted normal or elevated concentrations of protective proteins. A subgroup, however, exhibited diminished flow over time and an increasing tendency to oral candidiasis and a diminution in output of histatins.