Although ultrasound evaluation of the reproductive tract of stallions was introduced to veterinary practice long ago, this examination is not always conducted during routine breeding soundness evaluation. The objective of this study was to investigate the clinical relevance of routine ultrasound evaluation of the stallion's reproductive tract. Breeding soundness evaluation of 113 stallions was performed, including ultrasonography of external and internal genitalia. Various pathological conditions were detected using this technique, with the most frequent being varicocele, thickened vaginal tunics and cystic structures. Varicocele and thickened vaginal tunics were associated with decreased quality of semen, while cysts of the epididymal head, urethra and uterus masculinus were frequently associated with ejaculatory problems. These findings suggested that routine ultrasound evaluation of breeding stallions may be very helpful in detecting pathological conditions that may impact their reproductive career.