The author followed up the changes of the farmers health status and their working conditions for 4 years from 1972 to 1975. Meanwhile, appropriate health administration and education were carried out by the author. Results are concluded as follows: (1) The health status of the farmers were improved by changing the working conditions, such as shortening their working hours, and change of the way to use chemical substances for agriculture, while there were not close relationship between their health and changes of the working environment. (2) By enlargement of the size of vinyl-tent-houses, the improvement of health status of the workers were not observed. (3) According to the observed results mentioned above, the author concluded that the chemicals for agriculture such as pesticide have serious impact to farmers health, and he also pointed out that it was very important to consider the health hazards by vinyl-tent-house agriculture as occupational hazards.