Visually responsive neurons in the inferotemporal cortex of monkeys are known to modulate their activity in response to specific patterns, including complex shapes, objects, and faces. While neuronal selectivity in this region of the brain has been often examined, little is known about the maintenance of such selectivity over a period of days and weeks. Traditional recording techni- ques have provided only indirect information, and, given the suspected malleability of selective responses in these areas, it would be of great value to investigate the relative permanence of selective representations here. Recent advances in implantable electrodes have made it possible to record chronologically from isolated single units for periods of days and weeks. We tested monkeys on a simple fixation task, presenting a large number of complex patterns and images while monitoring action potentials with the implanted electrodes. We found that the stimuli elicited specific responses, and that the selectivity between neighbouring cells differed substantially. Furthermore, the diverse selectivity and temporal patterning characterising these neurons were generally maintained from session to session. The results suggest that individual neurons have remarkably specific and fixed roles in the analysis of complex stimuli over a period of days.