Analyses of the health costs in developing countries have mainly dealt with provider costs. This is in spite of the fact that the bulk of illness related costs is borne by households. Where studied, household time and financial costs have not been treated in a comprehensive way. However, an incomplete cost assessment will lead to an understimation of household costs. Using data from a household interview survey in a rural area of Burkina Faso, the authors carried out an exhaustive assessment of the economic cost of illness that households incur. Financial costs included out-of pocket expenditures for drugs, fees, transport to the treatment site, lodging and food for accompanying household members. Time costs, in turn, were comprised of production foregone both by the sick person and by healthy household members, who tended to the sick. Time costs amounted to by far the largest proportion (73 %) of total household costs. Of the total amount of illness related time loss of the average household, 45 % was due to the fact that healthy household members tended to or accompanied their sick kin. Of the financial cost items, expenditures for drugs or traditional products represented 62 %. When Western type services were sought, expenditures for transport, food etc., exceeded those for treatment fees. Total cost of illness was 4,002 F CFA/month for the average household. This amounted to 3.7 % of household income and to 6.2 % of household expenditures in the reference month. The authors discuss policy measures aimed to reduce household time costs. They point to the substantial underestimation of the financial burden that health care imposes on households, when these costs are assessed in an incomplete way. Finally, they call for great caution in taking the households' ''ability-to-pay'' far health care for granted.