The aim of this study was to evaluate the effects of animal-assisted activity on self-esteem, control over activities of daily living, and other psycho-physiological aspects among Taiwanese inpatients with schizophrenia. Thirty participants were randomly assigned to either the treatment or control group. A weekly animal-assisted activity program was arranged for patients in the treatment group for 2 months. A questionnaire assessing self-esteem, self-determination, social support, and psychiatric symptoms was completed the week before and the week after the animal-assisted activity. Compared with the control group, the treatment group showed significant improvement on all measures except for social support and negative psychiatric symptoms. The results of this study showed that animal-assisted activity can promote significant improvements in many clinical aspects among inpatients with schizophrenia. Therefore, animal-assisted activity should be integrated into the treatment of institutionalized patients with schizophrenia.