Hepatitis B and the acquired immunodeficiency syndrome are serious diseases because of their poor prognoses. The increasing awareness of the latter has highlighted the need for adequate precautions against cross contamination. However, the risk to dental personnel is still far higher from hepatitis B than it is from the human immunodeficiency virus, and the hepatitis virus is more transmissible, especially because it occurs in saliva. The principal potential route of transmission to dental laboratory personnel is via infected impressions. A number of papers have appeared in the literature examining the effects of various disinfecting and sterilising procedures on the accuracy and surface quality of impression materials. This paper reviews this literature and draws upon the findings to recommend a protocol for the handling of impressions to prevent cross contamination.