This chapter examines research on the effects of acute alcohol intoxication and other drugs on memory performance. In laboratory eyewitness memory studies, alcohol intoxication has been found to reduce the quantity but not the accuracy of memory reports. People who were alcohol-intoxicated during the crime can also perform similarly on person identification tasks, although recent research with field participants indicates identification responses may be more liberal with relatively high doses. Finally, there is limited research on the effects of drugs on eyewitness memory. Research to date suggests memory reports are less complete but no less accurate when eyewitnesses were under the influence of cannabis compared to sober during the crime. The implications for the legal system are considered.