Aim: Various ethical and legal guidelines require dental practitioners to adequately design, prescribe and fabricate good quality prostheses. The purpose of this investigation was to examine the quality of written instructions and choice of impression trays and materials for both fixed and removable prosthodontics in Ireland and the United Kingdom.Materials and methods: A pre-piloted questionnaire was distributed to a number of large commercial laboratories geographically distributed throughout the United Kingdom and Ireland. Information was sought relating to the quality of written instructions and use of impression trays and materials for three forms of 'dental precision casting' - cobalt- chromium based removable partial dentures, full veneer porcelain-fused-to-metal crowns, and conventional fixed bridges.Results: Six hundred questionnaires were distributed, and information was received relating to 447 items of prosthodontic treatment ( response rate = 75%). Ninety-five per cent of cases were privately funded. Using pre-determined grading criteria, poor or no written instructions were provided in one-half of cases examined. One-half of master impressions were made using a plastic stock tray. The technician felt that material had been appropriately disinfected prior to being sent to the laboratory in only 57% of cases.Conclusion: The written instructions and master impressions examined in this study failed to meet the relevant ethical and legal guidelines in approximately 50% of cases.