Workers involved in the production of pentachlorophenol (PCP) may be exposed to one of its contaminants, hexachlorobenzene (HCB). PCP is produced commercially in the USA by direct chlorination of phenol with chlorine gas in the presence of a catalyst at gradually rising temperatures up to 200 degrees C. Other contaminants formed in PCP production are isomers of hexa-, hepta- and octachlorodibenzo-para-dioxin and isomers of tetra-, penta-, hexa-, hepta- and octachlorodibenzofuran. This paper presents the analytical results of personal breathing-zone, area-air and surface-wipe samples collected at a typical PCP manufacturing plant. The personal breathing-zone samples showed that workers were exposed to HCB concentrations ranging from less than 0.0001 to 0.12 mg/m3. Area-air samples taken throughout the manufacturing plant showed that HCB concentrations ranged from less than 0.0001 to 0.63 mg/m3. Surface-wipe samples showed contamination ranging from less than 0.1 to 3.7 micrograms/wipe.