A sample of 244 persons in northern California who provided care for individuals with possible or probable Alzheimer's disease was studied to examine the effect of association with companion animals on three indices of psychological health. 124 caregivers had regular contact with pets; 120 caregivers did not. Men who were attached to dogs scored better on some measures of psychological health than did men who had no pets. Women less than 40 years old who were attached to cats scored better on some measures of psychological health than did the same-age women who had no pets. Women aged 40 to 59 years who were attached to dogs scored worse on measures of life satisfaction and depression than did the same-age women who had no pets. The data suggested a positive indirect effect on caregivers' mental health through interaction between the pet and the patient, but small strata numbers precluded definitive conclusions. Association with pets appeared to temper some of the psychological stress associated with caring for a cognitively impaired adult among young female and male caregivers but not among middle-aged female caregivers.