Doppler ultrasound, a technology utilizing sound waves to measure blood flow, has significantly influenced microsurgery, involving intricate procedures under magnification. The history of Doppler ultrasound spans decades and showcases its pivotal role in improving surgical outcomes. In the 1950s, the basic principles of Doppler ultrasound were developed, building on Christian Andreas Doppler's 1842 description of the Doppler effect. By the 1970s, Doppler ultrasound found clinical applications in assessing blood flow and diagnosing vascular conditions. Microsurgeons recognized its potential in microvascular surgery during this period. During the 1980s, Doppler ultrasound was integrated into microsurgery, offering surgeons precise assessment of blood flow, particularly in procedures like free tissue transfers. The 1990s witnessed advancements, making Doppler ultrasound more user-friendly with higher resolution, enhancing its utility in assessing tiny blood vessels <5mm. In the 21st century, Doppler ultrasound remains a valuable tool in microsurgery, verifying blood supply adequacy before anastomoses and ensuring the viability of transplanted tissues. Its applications extend to flap monitoring, where it is crucial for assessing blood supply in transferred tissue, ensuring flap survival. The integration of colour Doppler and power Doppler modes in ultrasound systems has further improved the assessment of microvascular blood flow, allowing visualization of blood flow direction and velocity. The continuous evolution of Doppler ultrasound reflects its indispensable role in microsurgery, providing real-time information crucial for the success of delicate procedures.