Lycasin was included in diets fed to caries-active Osborne-Mendel rats for periods up to 8 weeks. The animals could tolerate up to 15-16% of Lycasin in dry-powder diets and up to 25% in pelleted diets before gastro-intestinal disturbance. Lycasin 80/55 at 25% in the diet was non-cariogenic, producing a very low level of caries, similar to that on a maize starch regimen and significantly below that on a sucrose regimen. At 16% in the diet D-sorbitol was even less cariogenic than Lycasin. Compared with the sucrose control, the reductions in caries scores were 89% on the sorbitol and 72% on the Lycasin 80/55 regimen.