Purpose: Platelet concentrates are used for regenerative periodontal and implant therapy. Up to now, no study has reported the influence of smoking on platelet-rich fibrin membranes. Hence, this crosssectional in vitro study aimed to analyze the influence of cigarette smoking on platelet morphology and fiber characteristics of both leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes. Materials and Methods: Sixty blood samples from both smokers (n = 34) and nonsmokers (n = 26) based on power analysis were collected and subjected for complete blood count and platelet morphology indices (mean platelet volume, platelet distribution width, platelet–large cell ratio, and plateletcrit). Leukocyte- and platelet-rich fibrin membrane (2,700 revolutions per minute for 12 minutes) and advanced platelet-rich fibrin membrane (1,500 revolutions per minute for 14 minutes) were prepared using a standard protocol. Thirtytwo platelet-rich fibrin membranes from 16 individuals were selected randomly from the two groups and were subjected to morphologic examination using a scanning electron microscope. Results: Both of the groups were matched for age. Red cell counts and white cell counts showed no statistical difference between the groups. Platelet indices of smokers did show slightly higher values than the nonsmoking group. Scanning electron microscopic analysis showed variations in the fiber width and pattern among smokers in both the leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes. Platelet cell morphology of the smoking group demonstrated spiky architecture, suggesting an active state, while in the nonsmoking group, the platelet cells were seen in clusters, suggesting a resting state. Conclusion: Scanning electron microscopic results show that long-term cigarette smoking does affect the thickness and arrangement of fiber architecture in both leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes and also could have an impact on activation of platelets. Schlagwörter: fibrin networks, growth factor, in vitro study, morphology, platelet-rich fibrin, platelets, smoking