Introduction Work-related mental health has increased considerably and become a major health and safety concern in New Zealand. It could affect work performance and productivity, and lead to a number of serious work-related injury and other illnesses. This study aims to explore impact of age and gender on self-reported work-related mental health among workers across all industries in New Zealand.

Methods Over 4,000 participants were recruited to the survey. Both online and telephone interviews were undertaken. A small number of face-to-face interviews were taken in high deprivation areas. Weighting age by gender within industry was applied to prevent bias and ensure the population representativeness.

Results Overall, 62% of workers mentioned experiencing at least one of work-related mental health issues (either depression or anxiety or stress) within 12 months prior the study time. The prevalence of work-related stress, anxiety and depression reported by workers was 59.8%, 31.2% and 19.7%, respectively. Work-related mental illnesses were reported statistically more prevalently in females compared to males (64.3% vs. 59.8%). Elderly workers aged 60 years and above were statistically less likely to report work-related mental health issues compared to other age groups. When stratified gender by age group, young female workers from 18 to 29 years of age were statistically more likely to report experiencing work-related mental health issues than any other groups of workers.

Conclusion Perceived work-related mental health is greatly affected by age and gender. Improving mentally healthy working environment could be more effective if workers’ age and gender are taken into account. Future studies are needed to identify any difference of demographic characteristics between self-reported work-mental health issues by workers and diagnosed mental illness resulting from work by doctors for better workplace health and safety interventions.