Between March and November of 1991, approximately 9000 workers from 43 different countries battled the burning oil wells in Kuwait To document the exposure of persons in Kuwait during the oil well fires to volatile organic compounds (VO Cs), we obtained samples of blood from 14 U S personnel in Kuwait City in May of 1991 (group I) and 40 American firefighters working in the oil fields in October of 1991 (group II) Concentrations of VO Cs in group I and group II were compared with those of a random sample of 114 persons in the United States (reference group) The median concentrations of VO Cs in group I were equal to or lower than those in the reference group We found significant differences between the median concentrations of several VO Cs in group II and the reference group Median levels of ethylbenzene were about 10 times higher among group II than among the reference group ( 0 53 g/l vs 0 052 g.g/l) Median levels of benzene, m-/p-xylene, o-xylene, styrene, and toluene among group II were more than double those of the reference group Although firefighters had higher median concentrations of VO Cs than the reference group, those American personnel in Kuwait not involved in fighting the oil fires had concentrations of VO Cs comparable to those in the reference group Blood VOC measurements indicate a significant increase in exposure to VO Cs in firefighters, but do not demonstrate this in personnel in Kuwait City.