One of factors affecting fertilization is the sperm’s ability to bind to hyaluronic acid, which should be present on the egg cell’s surface. In order to check this reaction, we use hyaluronic acid binding tests. During the test, at least 80% of sperm should bind to hyaluronic acid. If the binding is very weak, there is a small chance that these spermatozoa will fertilize the egg cell. So, semen with hyaluronic acid binding parameters below 80% gives much lower chances for pregnancy in case of natural attempts. Semen with such parameters should not be applied for insemination. In such patients, solely in vitro fertilization with micromanipulation is recommended.