Phthalate esters and phosphate esters in samples of indoor air from 27 houses in the Tokyo Metropolitan area were quantified using gas chromatograph/mass spectrometer and gas chromatograph/flame photometric detector after adsorption on to charcoal and solvent extraction. The median concentrations of diethyl phthalate, dibutyl phthalate (DBP), butylbenzyl phthalate, dicyclohexyl phthalate and diethylhexyl phthalate were 0.10, 0.39, 0.01, 0.07 and 0.11 microg/m(3), respectively. The median concentrations of tributyl phosphate, tris(2-chloroethyl) phosphate, triphenyl phosphate and tris(2-butoxyethyl) phosphate were less than 0.001 microg/m(3). DBP was detected at the highest concentration (6.18 microg/m(3)) in a new residential housing. This research indicated that exposure to phthalate esters through inhalation of air from the indoor environment is as important as dietary intake of phthalate esters, and can contribute to daily intake to a much greater extent than has been assumed hitherto.