A hygienical survey was carried out on the works handling manganese compounds in Osaka over a period from December, 1963 to January, 1964. 1) Air analysis of the working environment Manganese concentrations in the working atmosphere showed 2.3 to 17.1 mg/m3 (median 8.4 mg/m3) for the work grinding manganese ore, 3.8 to 8.1 mg/m3 (median 4.9 mg/m3) for the work manufacturing electrodes, and 1.9 to 21.1 mg/m3 (median 4.3 mg/m3) for the work manufacturing dry cell batteries. 2) Medical examinations A hundred and thirty four workers chosen from 12 factories were examined on their health. Four workers in the factories grinding manganese ore were suspected of manganese poisoning showing clear signs of disorders of the central nervous system. Slight neurological signs were observed in 11 of 47 workers grinding manganese ore, 4 of 32 workers manufacturing electrodes, and 7 of 55 workers manufacturing dry cell batteries. However, no particular findings were seen in the blood and urin examinations, and these results showed no significant correlation to neurological findings. 3) Recommendation for hygienical countermeasures On the basis of the results above, the following advices were given to the factories surveyed; improvement of the processes and equipments in the dusty working places, strict enforcement of periodic medical and environmental examinations, early detection and adequate treatment of the workers showing any pathological signs, and thorough-going health education for the workers.