Breeding season is just around the corner and most breeders dread the frustration of subfertility in certain broodmares. A thorough breeding history is key to diagnosing the cause of subfertility. Questions that address previous breeding management, stallion selection, and general wellness are important when performing a breeding soundness evaluation. Diagnostics such as trans-rectal palpation and ultrasound examination of the reproductive tract, vaginal speculum examination, digital cervical palpation, endometrial cytology and culture, endometrial biopsy, and hysteroscopic examination are useful in determining the cause of subfertility. Typically, a cause of subfertility can be determined utilizing the diagnostics mentioned above, but there may be some cases in which diagnostic test results are negative and yet a mare is still subfertile. So what’s next?