The patch test results from 1,000 patients tested with the ICDRG standard series are analyzed for positive reactions to potassium dichromate, nickel sulphate, and cobalt chloride. Nickel appears to be the most common sensitizer, especially among women, although false-negative reactions may occur if it is tested with a 2.5% concentration in yellow petrolatum. Chromate dermatitis is generally of occupational origin among men. It is also quite common among Belgian women, probably because of the widespread use of Javel (liquid bleach), containing sodium dichromate as a colouring and stabilizing agent. Positive patch test reactions to cobalt are generally accompanied by allergic reactions to nickel or chromate. Its role as a primary allergen, however, must never be overlooked. The relationship between these metals and hand and foot eczema is evaluated. The results of a follow-up questionnaire are given. More than 70% of the patients allergic to chromates or nickel continued to suffer from contact eczema after the diagnosis had been made and therapeutic measures taken.