Abstract: Safety and health at work are extremely important yet they still appear to be one of the most neglected factors in the industry. Almost 90% of accidents that occur in the workplace are due to human errors. While studies suggest that the lack of skills and experience among workers can significantly increase the prevalence of human errors, few studies actually investigate how stress, repetition, fatigue and environment can affect human error. Hence, this study aims to explore the significances of the effects of stress, repetition, fatigue and work environment on human error in manufacturing industries. Questionnaires were constructed and distributed to several manufacturing firms across Peninsular Malaysia. A total of 200 questionnaire responses were collected back. The responses were analysed using descriptive, reliability, correlations and multiple linear regression analyses. It was found that human error is significantly affected by the 4 major factors explored in this study. A total of 48.8% of the variance in human error can be explained by stress, repetition, fatigue and work environment. The results of this study can act as useful protocols for manufacturing managers and policymakers in identifying critical factors to iron out problems such as human error and accidents at the workplace.