A questionnaire survey was conducted on 5,523 taxi drivers in Osaka Prefecture to investigate their working conditions and daily life as well as characteristics of their health condition and various effects on health, especially on their cardiovascular system. The major results of this survey were as follows: 1) The rate of subjective symptoms, morbidity rate and rate of poor physical condition over the past year in the taxi drivers were higher than those of the control group. Among the subjective symptoms, the rate of gastrointestinal disorders, fatigue, musculoskeletal system disorders, sensory system disorders, hemorrhoids, etc. was especially high. 2) Work shift, density of work, years of experience in taxi-driving, frequency of fright while driving, pattern of taking meals, way of recuperation on rest days or holidays, obesity, smoking, and intake of coffee and alcohol were found to be factors affecting the health of taxi drivers. 3) Nearly half of the respondents said that they would like to quit or change their job with as much as 62% giving "condition of health" as reason. On the other hand, the rate of heart-related symptoms such as palpitation, and breathlessness did not differ from that of the control group. The possible reason for this deduced from the foregoing results, is that there were some who had changed or quit the job at an early stage for health reasons such as heart trouble and severe physical and mental burden resulting from taxi driving. 4) Many taxi driver are obese and the rate of those with heart-related symptoms was considerably high among those classified as obese. In addition, the results showed that those with longer driving experience tended to be obese.