It is well known that there are many kinds of strains of fungi in the atmosphcre and important problems of the relationship between these microorganisms and human bcing. The survcy vas performed to find the source of fungal infection by the determination of pathogenic fungi at the sites of much frequented travelIed, very confused perdestrian traffic, contaminated indoors of hospital huilding. For the purose of clctermining the aerial fungi collected at the selected areas in clinic of Seoul National University Haspital (out-patient roorn and corridor, kitchen room, corridor of operating room, pharmacy floor, supply room and in-patient rooms) by sampling method of gravity seilimentation by 5 minutes exposure of Sabourands glucose agar plate (5cm. diarmeter dish) and identified the fungi macroscopically and microscopicalIy. The rusults are as follows; 1. From 8 indoor ares of hospital, 441 colonies were sampled and average number of funga1 co!onies in each of the agar plate was computed to 3,675 colonies. Total generas abtained by cultivation were 9 generas, and the common fungi in air were hormodcndrurn(18. 59%), penicillium(17.68%) and aspergilIus (16.55%) in crder frequency. 3. No pathogenic fungi were isolated, and it is assumed that there is no radical problem of infection source in hospita.I indoors practicalIy.