The impact of real-time ultrasound on the study of reproduction has been dramatic, and portable ultrasound machines have given clinicians an added tool for diagnostic reproductive management. Ultrasound is commonly used to monitor uterine anatomy, involution, and pathology, and has been used to detect pregnancy, study embryonic mortality, monitor fetal development, and determine fetal sex. The applications of ultrasound include the ability to monitor follicular characteristics, ovarian function, and aid in follicular aspirations and oocyte retrieval. As technology improves, technicians will use the internet or video conferencing for ultrasound image analyses. Although the technology of reproductive ultrasonography holds much promise for improving reproductive efficiency in beef and dairy cattle, new research on the practical implementation of early pregnancy diagnosis into a systematic synchronization and resynchronization system in lactating dairy cows has identified some pitfalls and limitations of early pregnancy diagnosis using transrectal ultrasonography.