One or more cells of Corynebacterium renale strains (serologic types, I, II and III), which possessed numerous pili, frequently were attached to BHK-21 cells, primary dog kidney cells, and primary rabbit kidney cells. The percentage of the cultured cells to which C renal cells were attached was about 70%. The percentage was less with cells of C renale possessing fewer pili, around 30%. After C renale was treated with the homologous anti-pili serum, the percentage of BHK-21 cells to which bacterial cells were attached was even less (22%). In electron micrographs, the pili of C renale were observed to attach themselves to the membranes of BHK-21 cells. The adhesive property of the pili of C renale to tissue culture cells was thus demonstrated.