The purposes of this research were to examine the presentation ability achievement of fourth-year undergraduate engineering students at King Mongkut's University of Technology North Bangkok, Thailand after they studied how to give investigation report oral presentations using the genre-based approach (GBA), and to determine the attitudes of the students towards the GBA. Data were collected using pre- and post-tests, a questionnaire, semi-structured interviews, and student logs. The results revealed that the employment of the GBA in teaching oral presentations was effective, and the students' attitude toward the genre-based lessons was positive. Learning how to write investigation reports prior to how to present them familiarized the students with the vocabulary and other important information for the presentations. The lessons allowed the students to practice with constant feedback and support from the teacher and their peers, leading to better achievement on the post-test and a positive attitude toward the teaching method.