A contingent valuation survey was conducted in Kumasi, Ghana, to estimate households' willingness to pay for two types of improved sanitation services: improved ventilated pit latrines and water closets connected to a sewer system. Over 1200 randomly selected households throughout the city were interviewed. Most households were willing to pay more for improved sanitation service than they were currently paying for their existing sanitation system (mostly public and bucket latrines), but in absolute terms the potential revenues from households are not large, of the order of US $1.40 per household per month (about 1--2% of household income). The results of the study confirm the conventional wisdom that conventional sewerage is not affordable to the vast majority of households without massive government subsidies. On the other hand, it appears that only modest subsidies are required to achieve relatively high levels of coverage with on-site sanitation (improved ventilated pit latrines). This is because improved ventilated pit latrines are much cheaper than conventional sewerage and because most households are willing to pay about as much for a ventilated pit latrine as for a water closet connected to a sewer. Several tests were conducted to check the accuracy of respondents' answers to contingent valuation questions. The findings indicate that contingent valuation surveys can be successfully carried out in cities in developing countries for public services such as sanitation and that reasonably reliable information can be obtained on household demand for different sanitation technologies. ¿ American Geophysical Union 1993