The cariogenicity of frequent rinsings with aspartame and sorbitol was studied in the rat caries model with animals randomly assigned to four oral rinse groups (16 rats/group): 0.05% aspartame, 20% sorbitol, deionized distilled water, and 20% sucrose; all solutions at pH 3.0. After rinsing five times daily for 21 days, mandibular molars were scored for caries. Smooth surface, proximal and morsal caries scores did not differ significantly between groups. Moderate dentinal sulcal caries for the sucrose group was significantly greater than in the aspartame, sorbitol, and water groups (p less than 0.05). Rinsing with 0.05% aspartame (similar in pH and concentration to that found in carbonated beverages) or sorbitol did not potentiate caries activity.