A study of the vaginal yeast flora in pregnant women living in Cusco and in its region (Peru), located approximately 3000 m above sea level, is reported. We observed 300 pregnant, healthy and non-diabetic women who attended a gynaecological clinic in the Lorena, Regional or IPSS (Instituto Peruano de Seguridad Social) hospitals in Cusco. A comprehensive clinical history was obtained from each patient. It included age, work, parity, time of pregnancy, use of contraceptives or antibiotics, type of vaginal symptoms, type and amount of vaginal secretion. The yeasts were isolated from 44.3% of the cases. The positive cases were more frequently found in the following categories: 20-30 year-old patients (69.2%), ninth month of pregnancy (49.6%), first pregnancy (41.4%), no delivery (58.7%) and no abortion (66.9%). Most women complained of leukorrhea (75.9%) with mucus, scarce without odour (18.8%) or lumpy, regular, without odour (15.8%) secretion. The yeasts isolated were Candida albicans (66.2%), other Candida species (12.8%), Torulopsis glabrata (8.3%) or other Torulopsis species (2.2%), Saccharomyces cerevisiae (7.5%), Rhodotorula sp. (1.5%) and Trichosporon cutaneum (1.5%).