Accounting for the endogenous relationship between health and hours worked, the goal of this study was to estimate the effect of mental health on the working hours of nursing professionals. The impact of hours worked on mental health was also investigated. The data was based on the Work Outcomes Research Cost-benefit (WORC) survey conducted in Australia during 2005 and 2006. The study sample of 6086 nurses represented ~15 per cent of nurses in Queensland. Analysis involved the use of simultaneous equations estimated with Generalized Method of Moments. The analysis of the data identified an endogenous relationship between mental health and hours of labour supplied. The findings revealed that among Queensland nurses, a deterioration of mental health was associated with a reduction in hours worked and increasing hours worsened mental health. The findings imply that an effective approach to meeting nursing shortages should include strategic attempts to improve the mental health capital of nursing staff. Previous studies have shown resilience training in the workplace as effective in increasing the supply of labor.