A study of contamination by polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (1336363) (PCBs) at a multibuilding facility was conducted. Surface wipe and dust samples were obtained at an unspecified multibuilding installation that included an incinerator where PCB askarel had been burned 12 years previously. These were analyzed for PCDDs, PCDFs, and PCBs utilizing gas chromatography with electron capture detection or gas chromatography/mass spectrometry. Widespread contamination with PCDDs, PCDFs, and PCBs were found. PCB concentrations were 100 to 1000 times that of the PCDFs and PCDDs. PCDDs found included 2,3,7,8-tetrachlorodibenzo-p- dioxin (1746016), heptachlorodibenzo-p-dioxin (35822469), and octachlorodibenzo-p-dioxin (3268879) as well as other tetra, penta, and hexachlorinated isomers. PCDFs found included 2,3,7,8- tetrachlorodibenzofuran (51207319), octachlorodibenzofuran (39001020), and other tetra, penta, hexa, and heptachlorinated isomers. The authors conclude that the PCB source was probably improper incineration of PCB askarel at the incinerator. The combustion products were airborne and entered the buildings by way of the air intake vents. The pattern of PCDDs and PCDFs, however, does not match that expected from incineration of PCBs. The PCDD and PCDF pattern indicates pentachlorophenol contamination, but no evidence of pentachlorophenol contamination or incineration has been found at the facility. It is not known what effect, if any, the long period of time between the incident and sampling at the facility had on the results obtained.