Introduction: Research has reported that smiles facilitate social relationships. However, the effect of a smile on driving behavior has received less interest. Method: This study attempts to evaluate how a pedestrian's smile influences an oncoming driver's behavior. In the first part of our study, male and female research assistants waiting at several pedestrian crossings were asked to smile or not at oncoming drivers. Results: It was found that a smile increases the number of drivers who stop. The same effect was observed when the pedestrian tries to cross outside the pedestrian crossing. Finally, this study shows that motorists drive slower after they see a pedestrian smile, suggesting that a smile can induce a positive mood. Practical applications: This leads to motorists stopping more readily and driving more carefully. These results also suggest that pedestrians may increase their own safety by using appropriate nonverbal signals toward drivers.