In this study, free version of MEDLINE database in the web which is PubMed and three Commercial versions which are Ebsco, ISI and First Search were Chosen. These Versions were gathered in five different features including: general information, searching features, display options, retrieval options and unique features. Then by use of comparative survey they were compared. The results showed that Ebsco has the best user interface features, followed by, PubMed, ISI and First Search. Of course when choosing a database one should have in mind the level of end users, their information needs and the budget of the library.