In general, the recommendation of the World Health Organization is 3-5 days of abstinence. However, based on laboratory studies and our experience, we have seen that in cases where there is a need for [search rare sperm cells] , increasing the number of days of abstinence to 10-14 days increases the chance of finding sperm in the ejaculate, since more sperm cells (provided, of course, that there is sperm production at all) will accumulate in the epididymis before emission.