Disclosed is a method for the determination of DNA fragmentation in animal sperm. It particularly refers to a procedure to evaluate the integrity of the chromatin/DNA of the sperm by means of a treatment of the sample with a denaturing solution followed, optionally by a stain; a subsequent treatment with a lysis solution that does not contain a protein denaturing detergent, followed, optionally, by a stain; and an evaluation of the integrity of the chromatin/DNA. The present invention also refers to a Kit to evaluate the quality of the sperm of animals which includes a DNA denaturing solution and a lysis solution that does not contain a protein denaturing detergent.