This chapter focuses on the common methods for stallion semen evaluation that practitioners should be familiar with, for assessing sperm quality and stallion fertility. Amongst the methods reported for stallion semen collection, the use of an artificial vagina is the most common and practical for veterinary practitioners. Determination of total sperm numbers in the ejaculate is fundamental to classify the reproductive potential of the stud, as well as to adequately prepare a breeding dose for artificial insemination. Estimation of sperm motility (or motion characteristics) is a fundamental test for the assessment of sperm quality and stallion fertility. Sperm morphology is considered a fundamental test when assessing stallion potential fertility, given that changes of sperm morphology reflect the stallion's intrinsic capacity to produce high-quality sperm. Historically, sperm morphological features were divided into primary, secondary, and tertiary abnormalities. Other classification systems classify sperm morphological abnormalities into major or minor abnormalities.