This paper proposes two models for evaluating Pharmacy Information Systems (PIS) on their user satisfaction, thereby exploring one of the major requirements in designing PIS for pharmacy networks. The first model is developed to measure pharmacies' satisfaction with their PIS and the second model is developed to specify the determinants of PIS satisfaction. Both models were validated by data from 142 members of a Dutch pharmacy chain. Based on the user satisfaction model, the explanatory model showed that Information Technology (IT) experience and knowledge are the most important drivers for pharmacies' PIS satisfaction. The implications for the evolution of PIS in pharmacy chains are discussed.