Factors associated with oral candidiasis in 51 diabetics were examined. The prevalence of oral yeast infection was 49 (n = 25)%. The association with diabetic control, as measured by fasting blood glucose concentration, urinary glucose concentration, and glycosylated haemoglobin, with the presence of yeast was analysed in the 51 diabetic patients. Glycosylated haemoglobin above 12% was strongly associated with oral yeast infection (odds ratio = 13.00) (p less than 0.001), while fasting blood and urinary glucose concentrations were not. The risk of oral candidiasis among diabetics wearing dentures was significantly higher than among dentate diabetics (odds ratio = 4.78). After controlling for the effect of denture wearing, glycosylated haemoglobin greater than 12% remained highly predictive of oral yeast infection, particularly among diabetics without dentures.