ICSI is a reproductive technique in which a single sperm is injected directly into a mature egg. It differs from the traditional fertilization technique used in IVF, so-called insemination, which involves mixing an egg and sperm in a cup. This technique in the treatment of infertility is prescribed for such reasons as low sperm motility, low sperm count, abnormal sperm morphology, azoospermia – the absence of sperm in the ejaculate, reduced ability of sperm to penetrate the egg. Among the advantages of this method is that ICSI fertilization occurs in up to 80% of all eggs used in the treatment procedure and that ICSI allows selecting the best quality of sperm for introduction into the egg. Thus, intracytoplasmic sperm injection is an advanced reproductive technique used in in vitro fertilization that makes pregnancy possible for couples who would otherwise have little chance of conceiving.