The goal of this study is to look into the manufacturing industry's industrial relations climate, trade union characteristics, and trade union effectiveness in Peninsular Malaysia. Data was collected from 137 manufacturing trade unions using a questionnaire-based survey. The findings reveal that the state of industrial relations and the characteristics of trade unions have a considerable impact on trade union effectiveness. This study focuses solely on the trade union effectiveness from the standpoint of trade union leaders. The findings provide crucial information to trade unions and the government about the factors that influence the effectiveness of trade unions.