The purpose of this investigation was to test the effect of chewing gum sweetened with either sorbitol (LG) or sucrose (SG) on the growth of plaque on tooth enamel surfaces. Nineteen dental students, in a balanced crossover design, chewed the two gums for 5 days without normal oral hygiene practices. The control treatment was a 5-day non-chewing (NG) phase. A period of 9 days was allowed for normal hygiene between test phases. The chewing regimen required 20 minutes of use of one stick of chewing gum immediately after meals or snacks. The average number of sticks chewed was 3.8/day. Pre- and post-treatment plaque scores were recorded by two examiners using a Modified Navy Plaque Index (PLI) from 0 to 9 along each of four surfaces to assess six Ramfjord teeth. Pre-treatment mean PLI scores for the 3 test treatments were, NG = 2.0, LG = 1.9 and SG = 1.9. Post-treatment mean PLI scores were, NG = 3.6, LG = 3.3 and SG = 3.3. ANOVA of pre- and post-treatment scores revealed no significant differences between treatments. Post-treatment scores of the 2 chewing gums were then pooled, independent of sweetener. ANOVA of these data revealed chewing gum (LG + SG = 3.3) to cause significantly less plaque accumulation than no gum (NG = 3.6). In a no oral hygiene environment, plaque accumulation during use of sorbitol chewing gum or sucrose chewing gum was statistically the same. However, chewing gum, irrespective of sweetener, caused significantly less plaque accumulation than no chewing.