Background Smoking is the largest preventable cause of death in the UK and imposes a huge economic burden on society. Both the prevalence and extent of smoking are significantly higher among people with mental disorders than among the general population.

Aims To estimate the economic costs of the health effects of cigarette smoking among people with mental disorders in the UK from a societal perspective.

Methods This study uses the WHO's economics of tobacco toolkit to assess the costs of the health effects of cigarette smoking among people with mental disorders in 2009/10 in the UK. Based on the cost of illness approach, direct healthcare costs, indirect morbidity costs and indirect mortality costs due to smoking-related diseases were calculated to estimate the avoidable economic burden of smoking in people with mental disorders.

Results The estimated economic cost of smoking in people with mental disorders was £2.34 billion in 2009/10 in the UK, of which, about £719 million (31% of the total cost) was spent on treating diseases caused by smoking. Productivity losses due to smoking-related diseases were about £823 million (35%) for work-related absenteeism and £797 million (34%) was associated with premature mortality.

Conclusions Smoking in people with mental disorders in the UK imposes significant economic costs. The development and implementation of smoking cessation interventions in this group should therefore be a high economic and clinical priority.