The purpose of this study was to see the morbidity of menstrual disturbance after antipsychotic medication in schizophrenic women, and to compare the characteristics of drugs between regular and irregular menstrual groups. The subjects of the study were composed of 75 female patients who were admitted to psychiatric wards in Kwangju and Chonnam area. They were not medicated at least one month prior to admission, and had a normal menstrual interval(i.e from 24 to 32 days). We evaluated retrospectively at the point of three months after admission to see menstrual disturbance for those who have had no menstruation until 5-6 weeks after medication. Medication status means dosage and the sort of drugs. The results was shown as follows: 1) Irregular menstruation occurred to 39 of 75 patients(52%). They had irregular menstruation within two months after medication(94.88%) 2) Total patients' distribution according to drug potency was shown a significant difference both in irregular and regular group(p<0.05). The patients who medicated on high potent drugs have shown no difference between two groups, but the irregular group seemed to respond to intermediate potent drugs and normal group to low potent drugs. 3) There was a significant difference in Chlorpromazine equivalent average dose between irregular and regular group(p<0.0001) for three months after medication, and it also showed significant difference between two groups on high potent drugs(p<0.0001). The above results suggest that morbidity of menstrual disturbance is high in schizophrenic female patients in a short time who were medicated antipsychotic drugs and who were medicated on high dosage.