Objective:This study examined the effectiveness of a newly developed transdiagnostic preventive intervention for anxiety and depressive symptoms among workers in a pre- and posttest study design.Methods:Participants were recruited from six companies and one medical clinic. The program was developed based on Unified Protocol. The outcomes were anxiety symptoms (GAD7), depressive symptoms (BDI-II), and psychological distress (K6), measured at baseline, 3-week, and 6-week follow-up. A mixed model for repeated measures was conducted for the whole sample and for a subgroup with higher psychological distress.Results:Among 75 participants, this program showed no significant effects on improving any outcome in the whole sample, but a significant improvement of psychological distress among the high-distress subgroup.Conclusions:The program may be effective in improving psychological distress among those who have high symptom levels.