In an investigation of students' prejudicial biases against instructors who smoke, 61 female and 16 male undergraduates watched and listened to a 20-min lecture about parasomnias, completed a survey asking for instructor evaluation ratings and ratings of perceived learning, and completed a lecture-retention test with multiple-choice questions to assess actual learning. In a between-subjects design, the lecture was given by either a man or woman, who was portrayed as a smoker or nonsmoker. The instructors' sex and smoking status did not affect the students' perceived or actual learning (all p's greater than 0.05). However, a significant interaction on the instructor evaluation ratings revealed that students rated the female instructors equivalently (p = 0.78), but rated the smoker male instructor significantly lower than the nonsmoker male instructor (p = 0.01). These findings suggest that students hold prejudicial biases against male instructors who smoke, but that these biases do not affect student learning.