The present paper examines the perceived acceptability of biometric security systems by a sample of banking and university staff. Results from 76 respondents indicated that all biometric systems were perceived as less acceptable than the traditional password approach. Contrary to expectations, it was found that behaviourally based biometric systems were perceived as less acceptable than physiologically based systems. The acceptability of several methods increased as sensitivity of information increased. Conversely, for the password method a negative relationship between acceptability and sensitivity was found. Results are discussed in relation to the potential for some behaviourally based biometric systems to be perceived as capable of electronic performance monitoring (EPM). The need for more research addressing perceptions of security systems amongst employees is highlighted. © 1995.