The effect of smoking habit on flow rate, pH and lactobacillus and yeast counts of paraffin stimulated whole saliva was analyzed in an unmedicated adult population of 462 nonsmokers and 180 smokers. Regular but not immediate smoking was not associated with any significant changes in the salivary flow rate. The pH of stimulated whole saliva was in both sexes lower in smokers than in non-smokers, the differences between the groups being statistically significant. Smoking did not affect salivary yeast counts, but smokers did show increased proportions of high lactobacillus counts.