A comparative study of the behavior of chick embryo endothelial cells grown on various substrates was performed in order to establish the reliability and the limitation of both cell and organ culture methods. Following substrates were analyzed to compare these two different culture techniques: bovine serum albumin, pigskin gelatin and albumin + gelatin cross-linked by glutaraldehyde or carbodiimide, fibrin glue and negative control (Thermanox*). Parameters of cell growth and adhesion were calculated and compared with electron microscopic observations of cell morphology and of the extracellular matrix. Both culture methods provided complementary results and led to a similar classification of the biomaterials. However, the cell culture method exhibited a higher sensitivity to the surface properties of biomaterials which limited further experimentation. This was well illustrated by glutaraldehyde cross-linked protein membranes which did not support the growth of dispersed cells but enabled the formation of a cellular tissue in organ culture, thus allowing a cytocompatibility assessment. Endothelial cell morphology and extracellular matrix elaborated on biomaterials were compared to chicken blood vessels. Both methods showed that cells grown on fibrin glue and on gelatin or albumin + gelatin cross-linked by carbodiimide had a microscopic morphology similar to that of vessel wall. Organ and dispersed cell cultures provide complementary information relative to the cell behavior towards vascular prosthesis materials