The effective reporting of test results from medical field investigations was discussed using 47 representative evaluation samples. Of these, notification of results letters were available for 36 studies. These communications were demonstrations of 15 years of processes and procedures practiced by the investigators working at NIOSH. A variety of health effects were encompassed by these 36 investigations. A review of these various studies listed and discussed most of the important features that should be incorporated into a test results notification letter. The authors suggest that any communication of results should include: understandable language, between investigator and participants, in regards to content and technical material, a written interpretation of the results including a discussion of all uncertainty, promptness in reporting individual and overall data, and information regarding a medical followup. Investigators should be trained in the process of communicating the results of a particular field study to the participants.