The mass examination was carried out in Shakurenji, Kama- Village, Akaiwa Connty, Okayama Pref., where great many deathes have been taken place by infectious hepatitis; results were as follows: 1. 127 persons received the examination; it has covered 94.1% of the entire people. 2. Those who have had jaundice previously were enumerated as 5 cases; as it was just the season when infectious hepatitis was in vogue in other parts of the Prefecture, though slight in degree, it was imagined that probably in the past there might have occurred a few sporadic cases. Among those, 3 were taken record of as new victims of disease, 3. In 6 cases, the patients complained of certain pain, each having some sort of liver disturbance more or less. 4. There were 24 cases in which liver enlargement could be detected; its rate, 18.9%, while splenomegaly been discovered in only one case. 5. Two women in pregnancy were recognized, one sickened case, the other inapparent infection case. 6. As for wide-range judgment taken after the examinaton, must-be-treated case, 5, must-be taken-care-of case 5. inapparent infection 60, 70 in total. percentage of contraction, 55.1%, adding 3 cases starting disease as well as 3 deaths; thus, great total, 76 cases; its rate, 57.1%. 7. Percentage of contraction has proved high in thirties and above 50. By sex, females superseded, but as to age, no definite conclusion could be established. 8. In case those patients exposed would be divided by respective family and investigated, it has been revealed thus: (a) with families which have used a well in common with the family in which death case or at least patient was found, Percentage of contraction has proved high and almost in like degree, since many were adviced to receive treatment, or, be taken care of. (b) Families which employed a well in common, were recognized to have proved about the same ratio in infection, containing not a few ought to be treated or taken care of, which suggests us an infection due to a well. (c) Among the group of families, whose relatives died of this disease, master of the house who had presented himasdlf over the funeral diet has been found to have taken infection alone.