This study tested the interaction effect of the instructor's eye gaze (direct gaze vs. averted gaze) and facial expression (happy face vs. neutral face) on students' attention and learning performance in slide-based video lectures. University students (N = 120) participated in the experiment in a laboratory setting. The results of ANOVAs showed that students in the conditions that included the instructor's direct gaze paid greater attention to the instructor's face and paid less attention to the video lecture slides. However, direct gaze predicted better learning when the instructor had a happy facial expression. Our results suggest that the effects of an instructor's eye gaze are modulated by her facial expression in this educational context. The findings have practical implications for designing slide-based video lectures: an instructor is encouraged to look straight towards the camera with a happy expression.