The purpose of this study was to compare the characteristics between chronic CS2 poisoning group and non-poisoning group, to find out major factors for decision of chronic CS2 poisoning, to describe the characteristics of cerebral infarctions, and to find out the related factors of cerebral infarctions. The study subjects were 220 ex-employees from W company and the study period was from August, 1993 to November, 1995. The proportion rate of chronic CS2 poisoning was higher in older age groups and longer work duration groups. The rate differed by cerebral infarction, microaneurysm, other retina lesions, polyneuropathy, psychiatric lesions, and sensorineural hearing loss. The cerebral infarction was found to be mainly multiple and the frequently occurred locations were periventricular white matter, frontal lobe and basal ganglia. The logistic regression for chronic CS2 poisoning showed that the major factors were microaneurysm, cerebral infarction, polyneuropathy, other retina lesions, diastolic blood pressure, and sensorineural hearing loss. Among the approved group 117 patients were followed up continuously at the outpatient clinic, 62.4% of the patients had hypertension, 61.5% had polyneuropathy, 52.1% had cerebral infarction, 35.0% had hyperlipidemia, 29.9% had liver disease, 15.4% had psychiatric diseases, 6.0% had angina, and 4.3% had anemia. For the hypertensive patients, 1.9 kinds of antihypertensive drugs were needed to control the blood pressure, and the BP decreased from 164/101 mmHg to 131/81 mmHg.