Lay involvement in clinical audit has been advocated but rarely reported. Since early 1994 in the mental health unit at Airedale, Yorkshire, lay representatives have participated in all stages of clinical audit, Including selection of topics and methods, data collection and standard setting. After 8 months of lay involvement, all respondents to a brief questionnaire saw lay involvement as important, although none identified specific benefits that had already occurred. The paper outlines themes in respondents' perceptions of the benefits and problems of lay involvement and in their suggestions for minimising difficulties.