This publication serves as a guide to medical doctors and dentists in the evaluation and management of problems related to nickel allergy. The chemistry, analysis, and monitoring of nickel is explored. Recent advances in the immunology of nickel are dis-cussed. Additionally, sensitization assays for both humans and animals are presented. The clinical, genetic, and epidemiologic as-pects of nickel sensitization and nickel dermatitis are explained. Social and demographic aspects of nickel contact allergy are dis-cussed, as well as the topic of the nickel dermatitis as a pre-ventable health problem.