Unexplained infertility is a common phrase in the reproductive world. It is the term used when there is no cause found for infertility. A diagnosis of unexplained infertility is given to about 15-25% of heterosexual couples with infertility. It does not necessarily mean that there is no cause – rather, it may mean that the cause has just not been found. Infertility may be said to be unexplained if the woman is ovulating regularly, has patent fallopian tubes with no adhesions or endometriosis, if the man has normal sperm parameters and the couple have been having frequent intercourse at the time of ovulation for at least one year. The final diagnosis is made only after all the necessary tests have been performed and all results are found to be normal.