The evaluation of intelligence function is required for the aged chronic schizophrenic patients under the circumstance such as long-term hospitalization. However, there have been only a few reports on the degree and quality of intelligence dysfunction in aged chronic schizophrenic patients. In the present study, using Okabe's simplified intelligence evaluation measure and GBS (Gottfries, Brane and Steen) scale, the assessment of intelligence function was examined in aged chronic schizophrenic patients hospitalized for more than 15 years. Concerning the results, in the aged schizophrenic patients, mental functions such as concentration are markedly reduced, but short-term memory is relatively well maintained. Although nearly half of them are compatible at home or to society, many problems remain to be considered on their return to society.