To what extent does previous and existing health economics research directly address key health system financing issues facing mental health services in developing countries? By mapping WHO's health systems framework onto mental health, three key financing questions for mental health are identified: the sufficiency of resources for mental health; the protection of individuals or households against the economic consequences of mental ill-health; and the efficient use of available resources for mental health. Research efforts to date have mainly focused on the evaluation of intervention costs in relation to mental health outcomes (the efficiency question). There is a need to achieve a greater balance between economic analysis (aimed at identifying best buys) versus financial planning (scaling up the delivery or implementation of interventions shown to be cost-effective). In addition, a better understanding and clearer articulation of the negative impact of mental disorders at the household level is needed, together with ways of alleviating financial burden via appropriate and affordable pre-payment financing mechanisms.