Background: Interventions via cognitive-behavioral strategies are promising in smoking cessation among adolescents, by using the Transtheoretical model (TTM). Objective: To assess the effect of TTM- intervention program on smoking health risk, stages and process of change in smoking cessation, , decisional balance, and self-efficacyamong technical secondary school male students in Zagazig city. Methods: A quasi-experimental study conducted in two randomly selected technical secondary schools in Zagazig city, Sharkia Governorate, Egypt. Male smokers from one school assigned as an experimental group and those from the other school as a control group. The experimental group received interventions based on the stage of behavior change through group counseling followed by individual phone counseling for 10 months. Intervention evaluation was done through self-reported questionnaires assessing knowledge and TTM outcomes. Results: After the intervention, participants in the experimental group (32%) progressed from lower to higher stages of behavior change compared with those in the control group (1.9%). The participants who reached the action/maintenance stage were 13.9% in the experimental group versus 1.9% in the control group. There was a significant difference between two groups in the mean scores of knowledge, processes of change, decisional balance and self-efficacy (P < 0.000). Conclusion: The TTM-based smoking cessation intervention program was effective in inducing a positive movement in the stages of behavior change among adolescent smokers through improving knowledge, experiential and behavioral processes, decisional balance and self-efficacy.