Smooth pursuit eye movement, one of the reliable biological markers of schizophrenia, is not always abnormal in schizophrenic patients. Therefore the authors studied it in schizophrenic patients and normal controls and compared the results according to the presence or abscence of family history of psychosis and types (type I and type II). The results are as follows: 1) In the 18 normal control group (8 mole, 10 female), there was no sex difference in the responses of smooth pursuit eye movement. 2) In th 44 schizophrenic group (28 male, 16 female), there also was no sex difference in the responses of smooth pursuit eye movement. 3) In comparison of 44 schizophrenic group to 18 normal control group, there was significantly increased abnormal response in smooth pursuit eye movement in schizophrenic group (P < 0.005). 4) In schizophrenic group, there was no difference in the responses of smooth pursuit eye movement between type I and type II schizophrenia. 5) The presence or abscence of family history of psychosis made no difference in the responses of smooth pursuit eye movement in schizophrenic group. 6) Subdivision of type I or type II in each case of presence or abscence of family history made no difference in the responses of smooth pursuit eye movement in schizophrenic group.