Purpose: The primary aim of this study was to evaluate the gingivitis-reduction efficacy of an experimental manual toothbrush with CrissCross and tapered bristle technology in comparison with a marketed control manual toothbrush with traditional design and non-tapered bristles. In addition, the study compared the two toothbrushes for plaque-reduction efficacy. Methods: This was a randomized, controlled, parallel group, examiner-blind, single-center, 4-week clinical trial with adult subjects in good general health. All subjects had presence of gingivitis (at least 10 bleeding sites). The subjects were randomly assigned to one of two treatment groups: a manual toothbrush having CrissCross and tapered bristle technology (tapered group: Oral-B CrossAction Ultrathin manual toothbrush); or a traditional flat-trim design and regular non-tapered bristles (control group: Oral-B Indicator Soft 35 manual toothbrush). Subjects were instructed to brush twice-daily for 4 weeks with their assigned brush and a standard sodium fluoride dentifrice. At baseline, Week 2, and Week 4, gingivitis was assessed using the Mazza Modification of the Gingival Bleeding Index (Mazza GI) and pre-brushing whole-mouth plaque was measured using the Turesky Modification of the Quigley-Hein Plaque Index (TMQHPI). Results: 100 subjects (50 per group) were randomized to treatment and assessed at baseline, and 97 subjects (48 in the tapered group and 49 in the control group) completed the study. At both Weeks 2 and 4, both groups showed a significant (P< 0.005) reduction versus baseline in Mazza GI and number of bleeding sites, and the tapered group showed a significantly (P< 0.001) greater reduction from baseline for both these assessments compared to the control group. By Week 4 the tapered group showed a reduction from baseline of 17.9% in Mazza GI and 38.5% in the number of bleeding sites; the corresponding figures for the control group were 7.5% and 12.6%, respectively. Both groups showed a significant (P< 0.001) reduction versus baseline in TMQHPI by Week 4, with no significant (P=0.06) between-group difference.