Lactoferrin, lysozyme, interferon, and neopterin levels were determined in parotid saliva from 44 individuals with different clinical stages of human immunodeficiency virus (HIV) infection and 19 HIV-seronegative controls. The secretory output of individual components was calculated according to the fluid flow rate. No parotid interferon activity was found in any of the HIV-infected subjects or controls, and no significant differences in parotid lysozyme or neopterin outputs were observed. The lactoferrin output was significantly decreased in HIV-seropositive subjects in parallel with their markedly reduced parotid secretory IgA output. This combined deficiency of parotid lactoferrin and secretory IgA may well contribute to the frequent oral infections seen in subjects with HIV infection.