BACKGROUND: The aim of this study was to evaluate the effectiveness of individual-focused stress management training namely Deep Breathing Exercise (DBE) on self-perceived occupational stress among male automotive assembly-line workers. METHODS: A quasi-experimental study was conducted at 2 automotive assembly plants in Malaysia over 9 months, from January 2012 to September 2012. Assembly-line workers from Plant A received DBE training while Plant B acted as a control by receiving pamphlets on stress and its ill-effects. Intention-to-treat analysis was conducted among the self-voluntary respondents in Plant A (n=468) and Plant B (n=293). The level of stress was measured using Depression Anxiety Stress Scales-21 (DASS-21) stress subscale. RESULTS: Significant favorable intervention effects were found in Plant A (Effect size=0.6) as compared to Plant B (Effect size=0.2) at the end of the study in those receiving DBE. Time and group interaction effects were examined using the repeated measure ANOVA test in which there was a significant group *time interaction effect [F (1, 1) = 272.45, P<0.001]. CONCLUSION: The improvement in stress levels showed the potential of DBE training as part of Employee Assistance Program in the automotive assembly plant. Future studies should be carried out to assess the long term effects of an on-site relaxation training to provide stronger evidence for the introduction of DBE among assembly-line workers as a coping strategy to alleviate occupational stress.