Two fabrication procedures, radiation-induced polymerization and the interpenetrating network method, are shown to be sufficient for incorporating hydrogel polymer (hydroxyethyl methacrylate and n-vinyl-pyrrolidone) into silicone rubber, polyethylene terephthalate velour, and polyethylene tubing substrates. Graft amounts of 1-270% are recorded with water imbibition ranges of 26-363%. Microstructural properties are found to vary from a homogeneous gel through a granular material with voids of up to 70 micrometers. Critical point drying is found to be a simple, satisfactory method of preparing samples for examination in the scanning electron microscope;The paravertebral muscle implantation of hydrogel composite materials based on silicone rubber or polyethylene terephthalate velour substrates is shown to produce a range of possible responses from minimal encapsulation in the case of the silicone rubber materials to actual tissue in-growth in the case of the velour materials. The hydrogel/velour materials are shown to have a persistent inflammatory cell population which is consistent with previous reports on the velour material alone. No pathological processes which would disqualify these materials for further investigation are reported;A surface penetration method to incorporate the hydrogel into silicone rubber substrates is shown to produce materials with contact angles from 57(DEGREES)-95(DEGREES), without altering the silicone rubber microstructure. The blood response to these materials is studied in an ex vivo femoral artery-to-vein shunt which is sampled at 5, 15, 30, 45, 60 minutes. The course of platelet and white cell adhesion for the 60 minute period is presented and scanning electron micrographs are used to demonstrate platelet aggregation and other blood cell deposition.