During an epidemiological survey of 181 individuals working or residing in the Kalahari National Gemsbok Park, swabs were taken from the dorsal surfaces of their tongues to determine a possible association between oral yeasts and clinically observed oral lesions as well as other underlying conditions detectable by serum chemistry. Identification of yeasts was performed with a commercially available identification system, namely the ATB 32C (Montalieu, Vercieu). Yeasts were isolated from 30.4 per cent (n = 55) of individuals, of whom 43.6 per cent (n = 24) had only Candida albicans, 3.6 per cent (n = 2) had C. albicans together with other yeasts and 52.7 per cent (n = 29) had other yeasts. Many of these yeasts were not the commonly encountered clinical isolates. The results revealed a significant association (p < 0.02) between yeasts (n = 55) and low serum iron concentrations (n = 50). A highly significant (p < 0.001) association was also found between smoking (n = 112) and the presence of clinically detectable oral lesions, notably leukoplakia (n = 21) and mucosal atrophy. The findings of this study reveal that a significant association exists between the oral yeast flora and serum iron and glucose, as well as between smoking and oral mucosal lesions.