The purpose of this study was to (1) compare crevicular fluid flow in smokers and nonsmokers with clinically healthy gingiva; (2) compare crevicular fluid flow of smokers in the areas physically exposed to smoke (maxillary lingual) to that in areas not physically exposed to smoke (maxillary buccal); and (3) compare crevicular fluid flow in smokers and nonsmokers before and after 1 month of (500 mg) twice daily vitamin C supplementation. All sampled areas were required to exhibit clinical health for all measurements (gingival, plaque, and bleeding indices at 0). Ten smoking (at least one pack a day) and ten nonsmoking male dental students were subjects of the study. Areas sampled were midbuccal and midlingual of teeth 3, 5, 12, and 14. Smokers were found to have significantly less crevicular fluid flow than did nonsmokers. Lingual areas of smokers showed no significant difference from buccal areas in crevicular fluid flow. One month of (500 mg) twice daily vitamin C supplementation resulted in a significant decrease in crevicular fluid flow in smokers and nonsmokers. The effect of tobacco smoke on clinically healthy gingiva may be a physiologic result of vasoconstriction rather than a physical irritation