The purpose of this study was to measure users' perceived benefits of a picture archiving and communication system (PACS) upgrade, and compare their responses to those predicted by developers. The Task-Technology Fit (TTF) model served as the theoretical framework to study the relation between TTF, utilization, and perceived benefits. A self-administered survey was distributed to radiologists working in a university hospital undergoing a PACS upgrade. Four variables were measured: impact, utilization, TTF, and perceived net benefits. The radiologists were divided into subgroups according to their utilization profiles. Analysis of variance was performed and the hypotheses were tested with regression analysis. Interviews were conducted with developers involved in the PACS upgrade who were asked to predict impact and TTF. Users identified only a moderate fit between the PACS enhancements and their tasks, while developers predicted a high level of TTF. The combination of a moderate fit and an underestimation of the potential impact of changes in the PACS led to a low score for perceived net benefits. Results varied significantly among user subgroups. Globally, the data support the hypotheses that TTF predicts utilization and perceived net benefits, but not that utilization predicts perceived net benefits. TTF is a valid tool to assess perceived benefits, but it is important to take into account the characteristics of users. In the context of a technology that is rapidly evolving, there needs to be an alignment of what users perceive as a good fit and the functionality developers incorporate into their products.