This paper seeks to synthesise the disparate research to date that has been done on the temporal decay of service quality and satisfaction responses. We aim to verify if this measurement artefact exists and, if so, to see if its magnitude can be quantified and generalised across a range of conditions. Using the existing published results from various ad hoc studies to date that have looked at the issue, we quantify the reported decays in service quality and satisfaction scores. In addition, we extend the research into two new crosssectional studies in the catering and financial planning industries. Service quality ratings decay as the time since the service experience increases. The extent of this decay is generalisable to approximately a 10% decline in service scores over a one- to three-month period. The majority of the decay occurs within the first month of the service encounter and then this rate of decline slows down or stabilises. Practical implications: this research adds to the body of knowledge concerning moderators of service quality ratings. It makes an important managerial contribution through providing a generalised decay figure of about 10% that can be used by managers and researchers to separate the confounding effects of temporal decay from real changes in customers' service quality perceptions.