Deposit formation is an intrinsic problem of heat exchanger operation and has been recognized as such since the industrial revolution. Empirical approaches to counteract the detrimental effects of deposit formation range from a wide spectrum of additives, via modifications of heat exchanger design and processing conditions, to attempts of predicting the frequency of cleaning schedules. While fouling has long been neglected as a serious research topic, there has been a 'mini-boom' of fouling research during the past 10−15 years, with research teams all-over the world attempting to attack this problem. Nevertheless, the initial progress with respect to the analysis of fouling mechanisms and the effect of operating parameters on deposition has only produced few tangible benefits for industrial applications. It is, therefore, appropriate to review the progress resulting from almost 20 years of relatively intense fouling research critically, and to change the research strategy in those areas which have no further potential for innovative fouling mitigation strategies.