Expected slowdown has been proposed as a criterion to evaluate queue fairness. In this work we examine how the constant slowdown principle can be used as a basis for a queueing fairness measure. We propose the Slowdown Queueing Fairness (SQF) measure based on the principle that customers’ waiting time should be proportional to their service time. We analyze its properties and examine how they react to both seniority and service requirements. We also examine whether its behavior fits intuition. Its values for a variety of single-server scheduling policies as well as for multi-server architectures are derived. c 2007 Elsevier B.V. All rights reserved.