A very important aspect for organizations that provide healthcare services is to have fully functional and successful information systems. A successful hospital information system can contribute to high quality healthcare services provided to the patients of the hospital. In this paper, is presented the evaluation of the information system of Chios Hospital, “Skylitsio”. The survey was conducted using a questionnaire which consists demographic questions and questions that measure the factors of the DeLone & McLean success model. The participants of the survey were 71 users of the clinical information system. Cronbach’s alpha reliability test, descriptive statistics, and further data analyses to investigate the relations between the factors of the DeLone & McLean success model were performed. Based on the results, the users of the information system are satisfied with it, as well as they find the system useful and easy to use. The average value of the “information quality” is 3.78 out of 5, the “system quality” is 3.61, the “service quality” is 3.45, the “use” is 3.83, the “user satisfaction” is 3.46, and the “user benefit” is 3.76. The research concludes with a validation of the DeLone & McLean success model and it seems that the information system of the General Hospital of Chios is successful based on the users’ opinions.