The potential of virtual environments for teaching people with autism has been positively promoted in recent years. The present study aimed to systematically investigate this potential with 12 participants with autistic spectrum disorders (ASDs), each individually matched with comparison participants according to either verbal IQ or performance IQ, as well as gender and chronological age. Participants practised using a desktop "training" virtual environment, before completing a number of tasks in a virtual cafe. We examined time spent completing tasks, errors made, basic understanding of the representational quality of virtual environments and the social appropriateness of performance. The use of the environments by the participants with ASDs was on a par with their PIQ-matched counterparts, and the majority of the group seemed to have a basic understanding of the virtual environment as a representation of reality. However, some participants in the ASD group were significantly more likely to be judged as bumping into, or walking between, other people in the virtual scene, compared to their paired matches. This tendency could not be explained by executive dysfunction or a general motor difficulty. This might be a sign that understanding personal space is impaired in autism. Virtual environments might offer a useful tool for social skills training, and this would be a valuable topic for future research.