The purpose of this study was to evaluate criminal barristers' opinions and perceptions of clinical psychologists and psychiatrists as expert witnesses. A questionnaire was developed and posted to 148 criminal barristers; 62 (42%) were returned. As predicted, the respondents reported significantly more contact with psychiatrists than clinical psychologists, and had more faith in the expert evidence of the former. However, content analysis revealed they were sometimes unaware of when dual mental health expertise was beneficial in court. Most respondents were in favour of accredited training for expert witnesses. Clarity of language, firm conclusions, impartiality, and consistency were considered important factors for good practice. The findings emphasise the importance of accredited (quality assured) training for expert witnesses as well as training and/or guidelines for legal professionals regarding the instruction of expert witnesses. There is also a need for those in the psychological community to market their skills and expertise more effectively.