Purpose: To evaluate supragingival and subgingival plaque formation on the dentogingival area in smokers and neversmokers using the experimental gingivitis model and a plaque scoring system that considers the presence of an area free of plaque between plaque and the gingival sulcus called the plaque free zone (PFZ). Materials and Methods: Male volunteers, 9 current smokers and 10 never-smokers, refrained from oral hygiene procedures in the maxillary incisors and canines (test teeth) for 25 days. Under conditions of clinically healthy gingiva (phase 1) and gingival inflammation (phase 2), the supragingival plaque formation pattern was observed for 4 days in the dentogingival area. Gingival crevicular fluid was also measured. Plaque was dyed with fucsine and its presence was recorded by a calibrated examiner based on a 3-criteria scoring system: 0 - absence of stained plaque; 1 - presence of stained plaque and supragingival PFZ; 2 - presence of stained plaque and absence of PFZ, indicating that subgingival plaque formation has taken place. Results: In both phases, smokers presented a significantly lower relative frequency of sites with subgingival plaque compared to never-smokers (P 0.001). Mean gingival crevicular fluid was significantly higher in the presence of gingival inflammation for both groups (P = 0.001), whereas smokers demonstrated a significantly lower frequency of gingival bleeding than did non-smokers (23.6% vs 66.1%; P 0.001). Conclusion: Smokers presented significantly lower percentages of sites with subgingival plaque in all experimental periods and presented less gingival inflammation as shown by GBI and gingival crevicular fluid quantification. Schlagwörter: dental plaque, gingival crevicular fluid, gingivitis, smoking