Mirrors can enrich the environment of some social animals kept in isolation. In this study, the effect of mirrors on the behaviour of isolated, or partially isolated, caged rabbits was tested. In a changeover experiment, four treatments were investigated: isolated without mirrors; partially isolated (with a conspecific housed behind a partition) without mirrors; isolated with mirrors; and partially isolated with mirrors. Behaviour was recorded during the first hour for which the rabbits were in the cages with the stimuli, and then again after one week. Initially, the rabbits' alertness increased, which may be because they perceived the mirror image to be a potential threat. The mirrors also stimulated investigation by the rabbits, which initially scraped them rapidly with their forepaws (scrabbling) and sniffed them. Although sniffing was maintained until the end of the week, scrabbling was not, probably because the rabbits failed to elicit the normal reactions of a conspecific from their mirror images. Mirrors also reduced the time rabbits spent sitting in their living area looking out of the cage, and increased their behavioural complexity, as determined from the number of behaviours performed per minute. In a second experiment, the responses of seven rabbits to four stimuli were recorded: a conspecific; a toy animal; a mirror; and a blank card. The rabbits were presented with pairs of stimuli at either end of a marked board. The responses of the rabbits to mirrors were more similar to their responses to a blank card or to a soft toy than to a conspecific. Although the rabbits did not respond to mirror images as if they were conspecifics, the mirrors may have had benefits to the complexity of behaviour of rabbits in small cages.