Platelet adhesion to and blood coagulation activation by amphiphilic networks (i.e., water soluble acrylates crosslinked by hydrophobic polyisobutylene) have been investigated in reference to polyethylene (PE) and poly(vinyl chloride) (PVC) controls in vitro. Among the amphiphilic networks examined, that containing poly(N,N-dimethylacrylamide) exhibited lowest thrombogenicity and showed significantly lower platelet adhesion than PVC, i.e., the reference with the lowest thrombogenicity. The amphiphilic network containing poly(2-dimethylaminoethyl methacrylate) exhibited less thromboresistance as judged by the adherence of a large number of procoagulant platelets. According to these findings precisely tailored amphiphilic networks may give rise to materials with blood compatibility superior to those currently in use.