Stress fractures of the tibia are common causes of lameness of the pelvic limbs of young Thoroughbreds (TB). If not detected in time, they can progress to complete tibial fractures, which in most cases leads to equine euthanasia. Historically, nuclear scintigraphy has been the imaging modality of choice for the diagnosis of tibial stress fractures; however, it is a complex and expensive method and is not available in many countries. A preliminary, descriptive and retrospective study was conducted on 12 horses with an ultrasonographic diagnosis compatible with tibial stress fractures. The objective was to describe the use of B-Mode (BM) and Power Doppler (PD) ultrasonography for the diagnosis of tibial stress fractures in TB, between 2 and 3 years old, of both sexes, all with a history of acute pelvic limbs lameness. Ultrasonographic evaluations in MB and DP were always performed by the same operator using a portable ultrasound machine. Images compatible with incomplete stress fractures were obtained in 10/12 horses, and complete displaced tibial stress fractures were found in 2/12 of the horses evaluated. BM ultrasound combined with PD proved to be an accessible and effective method to visualize changes compatible with stress fractures on the cortical surface of the tibia in the horses under study.