The main purpose of this study is to examine the farmers' intention of pesticide use by using a combination of the theory of planned behavior, the expected utility theory, and the diffusion of innovation theory. The data were collected from 362 farmers in Quang Nam from April to December 2020 and were analyzed by a structural equation model. The analysis results show that farmers' intention to use pesticides is affected by many variable groups from the above theories. The combination of these theories limits the disadvantages of applying only one theory into studying the farmers’ intentions of pesticide use.