To analyze how a horticultural therapy affects behavioral psychotic symptom and sociability of schizophrenic patients, a study was performed with 48 schizophrenic patients in a psychiatric institution in Daejeon, Korea. The horticultural therapy was conducted twice a week for a total of 29 sessions for seven months. Pre- and posttest assessment of behavioral psychotic symptom and sociability was done. Data from 48 patients who were not absent from the tests more than five times, and who performed every test item, were analyzed T-tests. Positive symptom(t=10.261, p=0.000), negative symptom(t=7.285, p=0.000) and general psychopathology(t=7.711, p=0.000) showed significant increase after application of horticultural program. Sociability of patients related to expression of their own opinions and respect to other persons through verbal(t=-4.64, p=0.000) and non-verbal(t=-6.43, p=0.000) showed significant increase after application of horticultural program. Substance of conversation(t=-5.58, p=0.000) was also increased significantly. Considering such healing effects of the horticultural therapy, it appeared to be a treatment technique that can improve the psychotic symptom and sociability of the schizophrenic patients.