The study uses data from the Tanzania Human Resources Development Survey (1994) on willingness to pay (WTP) for desired quality of health care at lower-level health facilities to assess potential regressiveness of user fees - a disproportionately higher negative effect of user fees on utilization of health services among the poor compared with the rich. Despite reports of extensive bypassing of the lower-level health facilities in Tanzania, the WTP for quality health care at these health facilities is surprisingly large. WTP was lower among the poor, female and elderly respondents. Almost one-quarter of the poorest 40% of the population was not willing to pay even when the quality of services met their expectations. The results suggest that: the utilization of health services at lower-level health facilities can be increased by improving the quality of care; and the implementation of uniform user charges in the public facilities may be regressive, adversely affecting utilization among the poor, women and the elderly. An effective system of exemptions and waivers will be required for the very poor who may not be able to pay even when quality of services is improved. The findings of the study have policy implications for the Tanzanian government's recent attempts to expand cost-sharing through community health funds at lower-level health facilities, being introduced since 1998.