This article reports a study of the bacterial adhesion to prosthetic valve materials in vitro. The method for assessing the degree of bacterial adhesion to prosthetic valve materials was established primarily. The capacities of staphylococcus aureus(SA), staphylococcus epidermidis(SE), Escherichia Coli(EC) and Pseudomonas aeruginosa(PA) for adhesion to Dacron, Pyrolytic carbon and polytetrofluoroethylene (PTFE) were quantitatively determined by the plate counting and Gamma-ray counting of 125I radiolabeled bacteria in vitro. The results showed that the capacities of four types of bacteria for adhesion to Dacron, Pyrolytic carbon and PTFE coincided with the bacterial-growth curve. The capacities of four bacteria for adhering to Dacron were stronger. The adhesion of SE to Pyrolytic carbon was the strongest. The adhesion of PA Kept up a high level. The capacities of EC and PA for adhering to PTFE were the strongest. The results indicate that the capacities of different types of bacteria for adhesion to the same prosthetic valve material are different, and the capacities of one type of bacteria for adhesion to different materials are also different.