: The message delivered can be fact, fictive, informative, educative, or instructional. The presence and development of this Audio Visual Aid (AVA) is inevitable, considering the strengths can give more real descriptions and improve memory retention because it is more interesting and easy to remember. The type of this research was quasi-experimental research. This research aimed to figure out the effectiveness of health education by using AVA towards the change of Teenagers' Knowledge of Obesity. This research was conducted at State Junior High School 1 Pekanbaru. The population total number of 435 students to be the samples. The technique of taking the sample was by using Random Probability Sampling. Data-dependent T statistic test analysis with the degree of reliability 95% p=0,05. The research results show that before and after conducting health education at State Junior High School 1 Pekanbaru by using AVA media is proven more effective. Keywords: Obesity, Video, Audio Visual, Knowledge