The study examined the burden of out-of-pocket spending (OOPS) to households, because available data showed that OOPS dominates household expenditure on health in Nigeria. The study took place in rural and urban districts in Nigeria. A household questionnaire was used to collect data from 4873 households on their healthcare expenditures and payment mechanisms by using a 1-month expenditure recall period. Financing incidence analysis was assessed at the household level on the basis of socio-economic status (SES) groups and rural–urban location of the households. Concentration curves of OOPS were plotted with the Lorenz curve of total household expenditures to show the distribution of the burden of OOPS by SES compared with total household expenditure. The Kakwani index was computed to examine the overall progressivity or regressivity of OOPS. There was lack of financial risk protection for healthcare in the study area. The results showed that 3150 (98.8%) of payments were made using OOPS, nine (0.3%) using reimbursement by employers, one (0.03%) through private voluntary health insurance (PVHI), nine (0.3%) using instalment and 14 (0.44%) through ‘others’. The average monthly household OOPS was 2219.1 Naira. The Kakwani index for financing incidence of OOPS was −0.18, showing that OOPS was regressive. The most-poor SES groups and rural dwellers experienced the highest burden of health expenditure. Urgent steps should be taken by the government to increase or enhance universal coverage in the country with financial protection mechanisms such as the National Health Insurance Scheme in addition to possibly abolishing some of the user fees that cause high incidence and burden of OOPS. Copyright © 2013 John Wiley & Sons, Ltd.