Abstract —The influence of cigarette smoking on the vascular reaction during plaque induced gingivitis was studied in humans for 28 days. Sixteen healthy dental students, 8 smokers and 8 non‐smokers, aged 19–42 yr, volunteered for the experiment. A numerical method was used for the evaluation of the vascular reaction. With the aid of stereophotographs changes in the number of gingival vessels were followed during the experiment. It was found that the number of vessels identified increased over time during the experiment in both smokers and non‐smokers. However, in spite of the fact that the plaque accumulation rate was equal, the vascular reaction was less pronounced in smokers. At the end of the experiment after 28 days the intensity of the vascular reaction in smokers was only 50% of that observed in non‐smokers. The difference was statistically significant at theP‐level of 0.05. One week after termination of the experiment and reinstitution of oral hygiene the number of gingival vessels equaled the pre‐experimental values in both groups. The results indicate that the vascular reaction associated with plaque induced gingivitis is suppress