Intrauterine insemination (IUI) is a treatment option for couples with unexplained infertility. It can increase the chance of pregnancy compared to trying naturally, especially after a year of unsuccessful attempts. For couples newly trying, the monthly chance of pregnancy is about 20–25%, but after 12 unsuccessful months, the chance drops to 2–3% per month. IUI can increase this chance to around 10% per attempt. It is a straightforward procedure that allows fertilization to occur naturally inside the body. However, it does not always work, and after a few unsuccessful attempts (often 3 cycles), other treatment options may need to be considered.