An evaluation of possible exposure to pentachlorophenol (PCP) by residents in Madison County, Kentucky, who had obtained ammunition crate wood treated with PCP from the Blue Grass Army Depot was conducted. Serum and unconjugated urine levels of PCP were determined in 51 test cases and 47 control individuals and in 7 special cases (residents of log homes treated with PCP). In addition, air, food product, and wood samples collected at the residences were analyzed for PCP residues. The results showed smilar PCP levels in the serum and urine of the test cases and control individuals. No PCP was detected in the air collected from these groups' residences; and the levels of PCP exposure from the ammunition crate wood. However, high PCP levels were found in the serum and urine of the special cases, particularly three young children who had PCP serum levels above 1,000 ppb (40 times the control individual average). Air and wood samples from a special case residence also contained PCP. Thus, the special cases were being subjected to PCP exposure and additional studies on log home residences are recommended to define the exposure level and the possible adverse health effects. No hexachlorobenzene was found in any samples.