Purpose: To compare the cleaning efficacy of a battery powered toothbrush (Spin Brush classicTM) and a standard flat trim manual toothbrush (ADA reference brush) in a single blind cross over study. Materials and Methods: 76 healthy subjects took part in this study. Subjects were asked to abstain from all oral hygiene procedures for 48 hours. Plaque was scored with the Turesky modification of the Quigley Hein Index. Then the subjects brushed their teeth for one minute with either one or the other brush according to a predetermined randomisation schedule. Immediately after brushing, plaque was scored again. All plaque scoring was done by the same investigator who was blind with respect to the brushes used. Subjects were instructed to continue with their usual oral care routine for 12-14 days. After this period they came back to the study centre having abstained from all oral hygiene for 48 hours prior to the visit. The evaluation sequence was repeated, this time the subjects were brushing with the alternate brush. To compare the cleaning efficacy of the two brushes, the percentage plaque reduction was calculated. Results: Using the non-parametric Wilcoxon test for paired samples (pTM (pTM (pTM compared to 38.9±14.9% for the manual toothbrush (p=0.047), and for the proximal surfaces 32.7±14.6% and 36.3±13.7%, respectively (p=0.024). It is concluded, that both brushes removed a significant amount of plaque. The Spin Brush classicTM, however, failed to improve the plaque removing efficacy of a standard flat trimmed manual toothbrush. This study was sponsored by Oral-B Laboratories, Boston MA, USA. Keywords: battery toothbrush, manual toothbrush, plaque index