Purpose: To examine the effect of toothbrushing with different brands of regular (Meridol, Colgate) and whitening toothpaste (Pearl Weiss, Rembrant, Email Diamant) on bacterial adhesion onto enamel surfaces in vitro. Materials and Methods: Extracted intact human teeth were brushed twice a day, for 3 minutes with the tested toothpaste for a period of 7 days. Sucrose dependent adhesion of Streptococcus mutans to the tested teeth was measured using pre-radioactive labeled bacteria. Results: S. mutans adhered more to enamel surfaces, pre-brushed with the tested toothpastes, than to teeth which were not brushed. Different profiles of bacterial adhesion were recorded. Both Diamant and Rembrant toothpastes increased bacterial affinity toward the enamel surface as compared to the other toothpastes. Meridol and Pearl Weiss demonstrated a similar adhesion effect as the etching control while brushing with Colgate demonstrated the least bacterial adhesion. (Am J Dent 2003;16:58-60).