The aim of the present study was to determine the salivary pH in HIV (Human Immunodeficiency Virus) positive(+) and negative(-) patients and in a control group, for assessing if variations or changes in pH are related to the development of oral candidosis and the species isolated. The sample comprised 120 patients from the Infectology Unit of the Mexico General Hospital, and from the School of Dentistry, UNAM. Three study groups were performed: with oral candidosis HIV+, with oral candidosis HIV-, and a control group. All patients filled out a clinical data questionnaire and signed an informed consent document. A 2 ml sample of non-stimulated saliva was obtained from each patient. The pH was measured and the sample was cultured on dextrose Sabouraud agar. The Candida species determinations were performed by the API 20 C AUX system and statistically analyzed. In the HIV+ group, the pH mean was 6.17, with most prevalence of Candida albicans type I and pseudomembranous candidosis. In the HIV- group prosthesis users, the pH mean was 6.29, with most prevalence of C. albicans type I, but with erythematous candidosis. The control group showed a mean pH of 6.78. A statistically significant difference among pH values was found (F= 15.45 p<0.01). The present study revealed that in HIV+ patients, the most significant predisposing factors are: immunosuppression, antibiotic therapy, bad hygiene, anemia, leucoplakia, and diabetes. The salivary pH with acidic values (more in HIV+ patients) significantly favors candidosis development, specially for C. albicans and C. glabrata species and primarily the pseudomembranous and erythematous clinic types. The pH is not a determinant for Candida growth, but could affect the adherence and invasiveness of the yeast.