Health survey was done on farmers using an organofluoride (N-methyl-N-(1-naphthyl) monofluoroacetate) and the following results were obtained. 1. Forty-five point seven percent of the farmers had some complaints after spraying the agent, which included fatigue, headache, nausea, anorexia, diarrhea, insomnia or abdominal pain. 2. Blood pictures of the farmers after spraying the agent indicated slight decrease or no change or hemoglobin and erythrocytes with the tendency of a higher color index than normal, and leukocytosis with neutrophilia. These blood changes, however, returned to normal in 6 months after the use of the agent. 3. Increased urinary urobilinogen and glycosuria were present in some cases, but none showed proteinuria. 4. Liver function tests revealed an increased icterus index and positive CCLF in some cases, but no abnormalities were found in TTT, ZTT, transaminases. There appeared to be no clinically appreciable liver disease. 5. ECG showed slight bradycardia and elongated P-Q intervals within normal ranges but no arrhythmia. No heart disease was clinically manifested in any cases.