The purpose of this shorter communication is twofold: (a) to establish a relationship between vortex shedding lock-on and heat transfer enhancement from a tube in cross-flow in the light of new findings in the published literature; and (b) to report additional results on the lock-on behaviour of an in-line tube bundle in pulsating cross-flow not previously published. The discussion of the results demonstrates the potential use of flow pulsations as a means of heat transfer enhancement in shell-and-tube heat exchangers together with useful guidelines for further research. Given the large proportion of energy use of heat exchanger equipment in the process and power generation industries, even small benefits in the efficiency of such equipment can lead to significant energy savings.