Approximately one-third of Bangkok households rented their accommodation during the 1970s, and this proportion was slowly decreasing by 1981. Most rental housing is in row houses, but the proportion of apartments is increasing. Construction materials are evenly divided between concrete and brick on the one hand and wood on the other. A general inventory of projects in late 1986 revealed at least 100 formal-sector rental housing projects that were constructed within the previous 2 years. A sample of 11 of these projects was surveyed through interviews with project personnel, and members of 7 households in each project. The projects surveyed had on average 120 units each, suggesting that 4,000–5,000 units/year were recently added to the rental housing stock. About one-third of the units surveyed were found to be vacant. Thirty-one projects where rents were below $US64/month, 1 25% of the median household income in Bangkok in 1986, were selected for a second survey. Five different types of rental accommodation were identified: concrete apartments, wooden apartments, low-cost houses, row houses in land sub- divisions, and rooms and houses in land rental slums. Rents in these units ranged from $20–$64/month. They catered to small young households (average 3.1 persons) of a young age-group (average 28 years) mostly in the second income quintile ($140–$212/month). Eight low-rent concrete apartment projects were then assessed as to their economic feasibility. Most projects were found to be economically feasible, renting units for $48–$64 per month. All projects required land in good locations, valued at $40-$60/sq.m; as well as high densities (more than 94 units/1,000 sq.m). Their feasibility was found to be very sensitive to rents, construction costs and operating costs. Given present practices, it appears that such projects can indeed be replicated on a small scale, but more thorough demand studies are needed to determine whether large-scale low-cost rental housing projects should be undertaken by the National Housing Authority (NHA) or by the private sector at the present time.