For the purpose of cytological study of human ascites, the author conducted tissue culture of human non-pathologic ascites and investigated the cell count and the cell composition in the tissue culture by means of vital staining and carbon particle phagocytosis. The following are the results of the present investigations. 1. The average cell count proves to be 1161/㎣ and as for the cell composition definite phagocytes, which can be classified into the large and intermediate and small types, occupy 94.4 per cent of the whole, and it is found that the intermediate and small types occupy the majority in about equal proportion. Other cells such as serous cells, lymphocytes, granulocytes and mast cells can be observed in a small proportion. 2. The large and intermediate type of phagocytes are consisted of cells in such various stages as mature cells to decrepit degenerated cells, and they present variegated findings in vital staining and phagocytosis. However, in these cells the majority of them present scatteringly neutral red granules and carbon black particles in the cell doily but no successive liberation of carbon particles can be observed. 3. Mature cells believed to be the proper form of phagocytes present rosette formation of neutral red granules and the conglomeration of carbon particles within intra-cellular locus and no successive liberation of carbon particles can be observed. Judging from these and other findings (pseudopodial movement and cell morphology) it is suggestive that these cells are cells closely related to monocytes. 4. Although the small type phagocytes demonstrate an extremely poor stainability to neutral red and and a low power of carbon particle phagocytosis and differ somewhat in their morphology as compared to the large and intermediate types, they reveal the characteristics of the above mentioned mature cells. 5. By Janus green staining all the large, intermediate and small types of phagocytes are stained well, and many Janus green granules are found in the perinuclear area as well as in the indentation of the nucleus.