Attachment and growth of mouse flbroblast cells on block copolypeptides were studied in the pres once or absence of serum proteins. Cells are rapidly attached to she polymer surface within 30 min regardless of substrate in the presence of serum. The number of flbroblast cells attached on the poly mer surface coated by collagen was larger than thats on the bare surface. Attachment of cells Is as a whole suppressed to a low level by the addltion of sodium azide in the absence of serum. Thls suE gests that the active attachment of cells requires the biological metabolism taking place on polymer substrates. In the presence of serum protein, flbroblast cells are more rapidly grown on the bolck co polymer consisting of poly(T-benzyl L-glutamate) (PBLG) and polyoxypropylene(POP) than on other block copolymers. These results were in agreement wish the data obatlned by an Inverted ml croscope.