Health information systems (HIS) have provided a major leap forward in communication and management of health services. In this study, a system of pharmaceutical services, which is an HIS platform that enables pharmacists to communicate with hospitals, government health agencies and suppliers, was investigated. The study aims to assess and determine factors influencing health professionals' (pharmacists) adoption of the system. In this work in progress study, a new research model (P-TAM) was developed, and a survey was conducted with 2169 pharmacists from different regions of Turkey. Statistical analyses were performed in order to determine strength and reliability of the model. The results were promising in terms of determining factors associated with the adoption of pharmaceutical services. The findings were useful for identifying influential behavioral constructs in HIS. It is believed that this study will be a valuable asset for the literature as well as the researchers who are in the first phase of their study in assessing HIS adoption.