In the past decade, the number of Malaysians experiencing poor mental health (low mood, worry, feelings of tension and stress) has tripled from 10.7% in 1996 to 29.2% in 2015. This paper estimates the business cost of mental health in terms of absenteeism, presenteeism and staff turnover. On a national level, the cost of mental health issues in the workplace to the economy is conservatively estimated to be RM14.46bn or 1% of GDP in 2018.