Summary Introduction Accurate post operative assessment of free tissue transfers is challenging despite all the subjective and objective techniques available today. In our continual search to optimise patient outcomes, we introduced the Cook-Swartz probe into our clinical practice in May 2006. Methods We present our single centre experience in 103 patients undergoing 121 microvascular breast reconstructions and monitored using implantable Cook-Swartz venous dopplers between May 2006 and January 2008. Results In total, we used 145 probes on 121 microvascular breast reconstructions (DIEP=102, SIEP=15, SGAP=4) in 103 female patients. The mean operative time was 4h and 55min (μ=295; range 117–630; ó±101min) and we suffered 2 complete flap losses. A problem with the audible signal was noted in 15 patients (4 intra-operatively). We revised 14 of the 15. All fourteen had compromised anastomoses. In the remaining case, the patient was not returned to theatre as the primary surgeon was confident there were no other signs of vascular compromise. Overall, when using the venous doppler probe we found a false positive rate of 6.7% and 0% false negatives. Discussion We advocate the use of a Cook–Swartz probe which has been well received by both surgeons, nursing staff and patients, as an adjunct to traditional clinical monitoring techniques. We also include a comprehensive experience based technical discussion concerning its application, attachment, use and post-operative removal.