Secretion rate and buffer effect of resting and stimulated whole saliva, and number of lactobacilli and S. mutans in stimulated whole saliva were determined for 182 subjects, of whom 109 were cigarette smokers. For secretion rate, no difference between smokers and non-smokers was observed. The median buffer effect was significantly lower in smokers. The median numbers of lactobacilli and S. mutans were significantly higher in saliva of smokers. The number of lactobacilli was significantly correlated with number of cigarettes smoked per day. About 40% of the smokers had greater than or equal to 10(6) S. mutans CFU/ml, which was more than twice that of non-smokers. In a complementary study on 20 smokers, the immediate influence of cigarette smoking on secretion rate and buffer effect of stimulated whole saliva was investigated for 1 h after smoking. No significant effect was found.