Experiments were designed to investigate the potential stress of procedures commonly used for restraining mice and to discover whether habituation of the adrenocortical response occurred when chronic restraint was used. The study also examined the effect of chronic restraint on the faecal output of oocysts by mice trickle infected with Eimeria apionodes. The results showed that restraining mice for one hour was stressful and that restraining them repeatedly for one hour daily for seven or 21 days did not lead to habituation of the adrenocortical response. Restraint for one hour daily for seven days did not cause the recurrence of a clinical infection in mice which were chronically infected with E apionodes. Restraining mice for one hour daily for seven days before and for 14 days during the infection also had no effect on the prepatency, patency or intensity of an E apionodes infection.