The total effect of sucrose-splitting activity from three sucrose metabolizing enzymes has been investigated in "resting" saliva in contact with dental plaque material in 356 military recruits. Invertase effect is defined as the splitting of sucrose into equimolar quantities of glucose and fructose, dextransucrase as a glucosyl-transferase producing glucan and free fructose, and levansucrase as a fructosyl-transferase producing fructan and free glucose. Total monohexose and glucose production as well were determined quantitatively in each subject. Monohexose production was related to specific oral conditions, and a difference in tooth decay significant at a 5% level was found between samples with high and low enzyme content. The production of free glucose was lower than that of free fructose, significant at less than a 1% level. This may indicate that more glucose is bound to form with a high level enzyme content a slight increase in relative effect of dextranscrase was found. This was not statistically significant.