OBJECTIVES: This study describes the association of yeasts and denture stomatitis with behavioral and biologic factors. STUDY DESIGN: Seven hundred eighty 55-year-old citizens of Oulu, Finland, were examined clinically; 452 of them had complete dentures. Salivary yeasts and lactobacillus counts were detected through the use of Oricult-N and Dentocult-LB dip-slide techniques. Lifestyle factors were measured by means of questions concerning physical activity, tobacco smoking, alcohol consumption, and dietary habits. Other background variables used in cross-tabulations and logistic regression analysis were unstimulated salivary secretion rate, retention of denture, oral hygiene, gender, and socioeconomic status. RESULTS: The prevalence of denture stomatitis was greater among subjects with an unhealthy lifestyle, subjects with higher lactobacillus counts, and subjects with poor oral hygiene. Salivary secretion rate and smoking were associated with the presence of yeasts, but general lifestyle measures were not. CONCLUSION: The presence of yeasts tended to be associated with biologic factors, but behavioral factors reflecting lifestyle may be more important in the development of denture stomatitis.