This paper presents the results of an exploratory study designed to investigate whether or notparticipants felt that they were encroaching upon the personal space of an individual who became engaged in conversation using a mobile phone in a public place. The hypothesis being tested was that people would perceive themselves as being drawn into the personal or intimate zone (Hall,1966) of the person having the mobile phone conversation. The study also explored whether or not this was dependent on the perceived nature of the conversation, e.g.private (a telephone call from the bank regarding an overdraft request) or social (arranging to meet a friend for a drink). The data obtained from the study was analysed in two parts: analysis of video recordings of user behaviour during the trial and the data obtained from open-ended questions answered by participants after the mobile phone conversation had taken place. The findings suggest that participants felt that they were being drawn into the personal space of the receiver of the mobile phone call, regardless of the perceived nature of the call. Although some participants felt uncomfortable about this, others admitted they enjoyed the voyeuristic aspect of this type of situation. These findings are discussed in relation to Hall’s (1966) theory of interpersonal distance and suggestions are put forward of how to develop this exploratory work into a more formal research investigation.