A method for enriching nucleic acids with a length of less than 300 nucleotides from a sample selected from the group consisting of plasma, serum, a body fluid, a smear and a cell lysate, comprising the method steps of i) providing a fluid, preferably aqueous, phase P 1 comprising (α1) at least one nucleic acid with a length of less than 300 nucleotides, and (α2) at least one component different from said nucleic acid (α1), ii) contacting the phase P 1 with an anion exchange matrix to bind the nucleic acid (α1) to the anion exchange matrix, wherein nucleic acids are bound to the anion exchange matrix at a pH within a range from 3 to 7, wherein the anion exchange matrix comprises functional groups selected from the group consisting of amino groups, hydrazine groups and imine groups, which are at least partially present in cationic form at the conditions under which the aqueous phase P 1 is contacted with the anion exchange matrix and wherein the anion exchange matrix is present in form of a coating on magnetic particles and wherein for binding the nucleic acids the aqueous phase P 1 that has been contacted with the particles is continuously agitated, and wherein the magnetic particles are separated from the aqueous phase P 1 as magnetic aggregates, iii) optionally washing the anion exchange matrix with a washing buffer, wherein the nucleic acid (α1) remains bound to the anion exchange matrix, and iv) eluting the nucleic acid (α1) bound to the anion exchange matrix from the anion exchange matrix by replacing the aqueous phase P 1 or the washing buffer with an elution buffer to obtain an aqueous phase P 2 containing the nucleic acid (α1). i) providing a fluid, preferably aqueous, phase P 1 comprising (α1) at least one nucleic acid with a length of less than 300 nucleotides, and (α2) at least one component different from said nucleic acid (α1), (α1) at least one nucleic acid with a length of less than 300 nucleotides, and (α2) at least one component different from said nucleic acid (α1), ii) contacting the phase P 1 with an anion exchange matrix to bind the nucleic acid (α1) to the anion exchange matrix, wherein nucleic acids are bound to the anion exchange matrix at a pH within a range from 3 to 7, wherein the anion exchange matrix comprises functional groups selected from the group consisting of amino groups, hydrazine groups and imine groups, which are at least partially present in cationic form at the conditions under which the aqueous phase P 1 is contacted with the anion exchange matrix and wherein the anion exchange matrix is present in form of a coating on magnetic particles and wherein for binding the nucleic acids the aqueous phase P 1 that has been contacted with the particles is continuously agitated, and wherein the magnetic particles are separated from the aqueous phase P 1 as magnetic aggregates, iii) optionally washing the anion exchange matrix with a washing buffer, wherein the nucleic acid (α1) remains bound to the anion exchange matrix, and iv) eluting the nucleic acid (α1) bound to the anion exchange matrix from the anion exchange matrix by replacing the aqueous phase P 1 or the washing buffer with an elution buffer to obtain an aqueous phase P 2 containing the nucleic acid (α1).