Samples of stimulated whole saliva were collected from 176 dental students, and their teeth were examined both clinically and radiographically. Salivary flow; buffering capacity; numbers of lactobacilli, yeasts, and Streptococcus mutans; and DMFS and DS values were correlated to sucrase activity. The high flow-rate group had a lower (p = 0.0201*) sucrase activity than the low flow-rate group. The proportion of high (greater than or equal to 10 mumol/min x mg x 10(-3] sucrase activities among the highest density category of lactobacilli was 67%, whereas the corresponding proportion in the whole material was only 28%. Men had significantly (p = 0.0169*) higher sucrase activities than women. The other variables measured did not seem to have any significant effect on the sucrase activity values. In addition to sucrose consumption, other factors like the rate of salivary flow and the density of lactobacilli seem to influence the level of salivary sucrase activity.