A demonstration respite project for caregivers of older people with Alzheimer's disease was evaluated by a randomized experiment. Three hundred and sixteen volunteer primary caregivers were offered respite services and 315 completed the research portion without the offer of respite. The research indicated that even before the demonstration most families had some respite help in place. Of all those offered respite, 58% availed themselves of the offer. During the project year experimental and control subjects were equal in using slightly more services and there was no evidence that formal services had substituted for informal.