Many cases of male infertility are genetic and molecular leading to morphological and functional abnormalities of sperm. Development and use of assisted reproductive techniques, especially Intracytoplasmic Sperm Injection (ICSI? Polish no date), creates the risk of introducing an egg cell with abnormal sperm DNA (eg, impaired condensation and cuts). This can cause a lack of concept or early miscarriage. The article describes two tests (Sperm Chromatin Structure Assay and TUNEL), involving the use of flow cytometry for the early detection of disorders condensation and DNA integrity in a large number of sperm. These tests are important prognostic for fertilization in vivo and in vitro.