Pathologists have been establishing archives of human organs and tissue for research use for many years now. Controversy has arisen recently over these collections, particularly with regard to the right of patients or relatives to consent to removal and retention of tissue, genetic research using stored tissue samples, and commercial exploitation of tissue collections and genetic material. This paper discusses the ethics of reusing existing archives of tissue. New archives are established under much more stringent conditions than in the past. What rules should apply to existing archives? Guidelines to regulate such use are useful, but face serious difficulties in balancing the variety of public and private interests relating to tissue banking. Consent cannot be obtained retrospectively, but public trust can be established by open acknowledgement of the evolution of ethical standards and strict adherence to current best practice. Guidelines and standards vary from country to country, but ethical principles should not. The implications of this view for pathologists worldwide are discussed.