This Research Report discusses a study, initiated in June 1995, to identify and review cases in which convicted persons were released from prison as a result of posttrial DNA testing of evidence. As of early 1996, researchers had found 28 such cases: DNA test results obtained subsequent to trial proved that, on the basis of DNA evidence, the convicted persons could not have committed the crimes for which they were incarcerated. The study also involved a survey of 40 laboratories that conduct DNA testing. To identify cases that met study criteria—defendant conviction, imprisonment, and subsequent exoneration and release resulting from posttrial exculpatory DNA tests—researchers examined legal and newspaper data bases and interviewed a variety of legal and DNA experts.