Present information on the magnitude and composition of private health expenditure (PHE) in Mexico.Total PHE by state was calculated using the System of National Health Accounts and National Performance Assessment Survey 2002-2003 by means of elasticities and growth relative contributions.58% of the total PHE was private and 90% of this was out-of-pocket expenditure. Most of the latter is expenditure in ambulatory care and drugs. 60% of the PHE was concentrated in only six states. PHE was lower than public expenditure in six states.The magnitude of out-of-pocket expenditure in health is worrying, since it is the most unfair, inefficient and regressive way of financing health care. Health authorities should look for alternative ways to finance health care, like the Popular Health Insurance.