Tea tree oil, originating from Australia, is nowadays used worldwide as all-round home remedy. It is applied diluted or undiluted for the treatment of skin and nail infections, against lice, scabies, athlete's foot, and ringworms. Furthermore it is used topically as a local antiseptic for cuts and abrasions, for burns and insect bites. Tea tree oil is considered safe when put on the skin, but it may cause also skin irritation and swelling. In rare cases skin dryness, itching, stinging, burning, and redness have been observed. Skin irritation is mainly associated with the organic compounds, but may also be caused by allergenic metals, such as nickel, cobalt or chromium. Thus, the presented study focuses on the determination of selected skin-irritating metals in tea tree oil samples available on the European market.