Objective. The purpose of this study was to evaluate the effects of pet therapy on geriatric psychiatry inpatients. A demonstrable impact could lead to more Widespread or targeted use of animal companionship programs for hospitalized older persons. Method. The study design was a randomized, parallel-group control treatment trial with pretreatment and posttreatment measures. Fifty-eight subjects with chronic age-related disabilities who were patients of the Wills Eye Hospital Geriatric Psychiatry Unit were assigned to a pet therapy intervention group or an exercise control group for 1 hr a day for 5 consecutive days. Every subject was blindly evaluated with the Multidimensional Observation Scale for Elderly Subjects (MOSES) before and after the intervention week. Results. No Significant differences in MOSES scores were found between or within groups before and after the interventions. There was a nonsignificant tendency for subjects who received the pet intervention to have less irritable behavior after treatment. However, women with dementia who received either pet therapy or exercise intervention had improved irritable behavior scores after treatment. Conclusion. This pilot study demonstrates the need for further research on animal-assisted interventions with hospitalized elderly persons. Differential improvement in women with dementia also requires further investigation.