Postoperative monitoring of free flaps has traditionally been based on clinical assessment, interpretation of which may be subjective. The Cook-Swartz implantable Doppler probe enables continuous objective real-time monitoring of blood flow at microvascular anastomoses. We report our experience with a cohort of 181 consecutive patients operated on between 2019 and 2025. Arterial placement of the probe was preferred after an initial experience of venous monitoring, and provided a clear and easily interpretable signal. The device demonstrated excellent diagnostic accuracy, with a positive predictive value of 100% for the detection of vascular anomalies. However, early detection does not always guarantee flap salvage. Clinical examination remains indispensable, particularly for detecting venous thromboses that may be overlooked on arterial monitoring alone. The Cook-Swartz implantable Doppler system is a reliable easy-to-use adjunct to clinical monitoring of free flaps in head and neck reconstruction.