Smoking impacts on hemostasis and coagulation physiology is affected. Although this is well known, no previous research is available on the impact of smoking on fibrin network morphology. Here the authors show that smoking causes the fibrin network to have a netlike appearance in some areas, as well as areas where thick plaques are present. They argue that even in occasional smokers, fibrin, in the presence of thrombin, forms thickened areas that might be the cause of a thrombotic event such as stroke. Furthermore, it seems as if smoking impacts immediately on the fibrin architecture, and this therefore does not happen only over an extended period of smoking exposure. This information is important, particularly for women with additional risk during contraceptive use and pregnancy. The authors propose the term sticky fibrin phenomenon and suggest that this is the cause for thrombotic events during smoking.