The functional effect of partial ischemia of the rabbit urinary bladder was studied. Unilateral ischemia was created by ligation of one of the two vesical arteries that supply the rabbit bladder. The effect of 1-day, 1-, 2-, and 4-week chronic unilateral ischemia on in vivo and in vitro cystometry, and the functional response of the in vitro whole bladder model to field stimulation and bethanechol were determined. Within 1 day following the creabon of unilateral ischemia, the bladder became hyperreflexic with decreased compliance. This condition was observed in the 1-and 2-week groups. By 4 weeks, the hyperreflexia had decreased, and the compliance increased significantly. Peak pressure generation for in vitro whole bladder in response to field and bethanechol (500 pm) stimulation was maintained the same as control for all groups. However, the ability of the bladder to empty was diminished to about 50% of control values in the 1-day, 1-week, and 2-week groups. The ability to empty recovered to a significant degree by 4 weeks for both field stimulation and bethanechol. Our results show that the bladder function cannot be judged by pressure generation alone; a study of compliance and the ability to empty should be performed to give a true indication of the functional state of the bladder.