Pentachlorophenol (PCP) was, and still is, one of the most frequently used fungicides and pesticides. Its toxicity is due to interference with oxidative phosphorylation. Acute and chronic poisoning may occur by dermal absorption, inhalation or ingestion. Chronic poisoning occurs mainly in sawmill workers or people living in log homes treated with PCP-containing wood protecting formulations. Quantitative determination of PCP in urine and serum is useful to detect occupational or subclinical exposure. The clinical features of acute and chronic PCP poisoning can be classified systematically into effects on the skin, metabolism (fever), the haematopoietic tissue, the respiratory system, the central and peripheral nervous system, the kidney and the gastrointestinal tract. Although PCP is not classified as a human carcinogen, some epidemiological observations suggest that exposure to chlorophenols in general and PCP solutions in particular may result in an increased risk for certain malignant disorders such as nasal carcinoma and soft tissue sarcoma. There is concern that contamination of PCP-solutions with products such as chlorodibenzo-p-dioxins is the real cause of this suspected carcinogenicity. No specific antidote exists for the treatment of (acute) PCP poisoning. The basis of the treatment of acute poisoning is intensive supportive care with prevention of dangerous rise in temperature. Use of PCP-based products as indoor wood preservatives poses an unacceptable risk to human health.