Abstract: A method is provided for the manufacture of collagen fibers for surgical purposes, in which Achilles tendons or hides from cottle are decomposed in an alkaline medium and are mechanically treated after treatment with an acid, deswelled, crosslinked and dried, wherein that Achilles tendons are decomposed in an alkaline medium to an amino-nitrogen content of from 0.15 to 0.30 .mu.moles/g and after a hydrochloric acid treatment and washing to a pH value of from 2 to 4, the swollen collagen substance is reduced in thickness under pressure forming a two-dimensional network, then the individual longitudinal fibers are exposed by hackling, and then, after deswelling, the fibers are cross-linked with hexamethylene diisocyanate in the presence of a nonionic or cationic emulsifier and are dehydrated and further processed on textile machines.