FIELD: biotechnology. SUBSTANCE: invention relates to the improved method of preparing collagen from a solubilized and purified and, possible, pepsinized extract of native or atelopeptide collagen involving the following stages: (i) stirring stage and shift of indicated extract in the mixer with double cross cutter at step-by-step increase of initial rate of stirring by 500-1000 rev/min but without excess of the rate above 10000 rev/min and at step-by-step increase of temperature by 2-10 C, preferably, by 3-5 C. This procedure provides the increase of the parent environment temperature of extract up to the maximally controlled value, i. e. 50 C, not above and then ii) sterilization stage in a liquid medium of indicated extract to obtain sterile collagen in native or atelopeptide form. Invention relates to native or atelopeptide collagen of type-I obtained under conditions of the above-mentioned method and showing the following indices or properties: ratio α2(I)1/α1(I)2 is from 0.48 to 0.52; sterility in accordance with the standard of European Pharmacopoeia; the total nitrogen content: from 17.0 to 18.7%; hydroxypropline content: from 12 to 13.9%; collagen does not contain tryptophan, aminoglycans and polypeptides with molecular mass <95000 Da; lipids content is <1%; sulfur-containing ash is <2%. Invention relates to a pharmaceutical and/or parapharmaceutical, and/or medicinal-surgery, and/or ophthalmological, and/or cosmetic composition. EFFECT: improved method of sterilization, valuable medicinal properties. 13 cl, 4 dwg, 9 ex
