The purpose of this clinical trial was to compare the efficacy of a new flossing aid (Flosser) with finger flossing on preventing plaque and gingival inflammation. 35 adults who did not use dental floss routinely were assigned randomly to one of 2 treatment groups (Flosser or finger flossing) in a 2-period, single-blind crossover study. After prophylaxis, subjects were instructed to use the flossing aid or finger floss 1 x per day and to continue brushing for 30 days. Gingival inflammation (GI & BPI) and plaque (PI) were assessed prior to the prophylaxis and at 30 days. After a 30 day "washout" period, subjects were again reassessed for gingival inflammation and plaque, given a prophylaxis, assigned the opposite treatment (2nd treatment period) that they received the first treatment period, and assessed (GI, BPI & PI) after 30 days. Comparing the mean difference of the 30-day buccal interproximal scores between the treatment groups (flossing aid scores minus finger flossing scores) showed that the mean differences with 95% CI were: -0.013 +/- 0.067 [GI], -0.017 +/- 0.044 [BP] and 0.019 +/- 0.014 [PI]. No statistically significant differences from zero (0.05 alpha) were observed using the t-test. There was a high level of compliance (90%) with the prescribed regiment, and subjects preferred (56%) the flossing aid slightly over finger flossing. Even though there were no statistically or clinically significant differences in gingivitis and plaque scores between the 2 flossing groups, the positive inclination for the flossing aid makes it a desirable addition to the armamentarium of preventive dentistry.