Across-sectional survey was designed to determine health professionals' awareness and usage of online evidence retrieval systems in clinical practice. A questionnaire was used to measure professionals' behavior and utilization of online evidences, as well as, reasons and barriers on information retrieval. 439 nurses and physicians from public and private hospitals in Greece formulate the study's sample. The two most common reasons that individuals are using online information systems were for writing scientific manuscripts or filling a knowledge gap. A positive correlation was found between participants with postgraduate studies and information system usage. The majority of them (90,6%) believe that online information systems improves patient care and 67,6% of them had their own experiences on this. More support is needed to nurses and physicians in order to use the online evidence and as a result to improve the provided care and practices.