One of the most important factors challenging the issue of "information storage and retrieval" in the Internet environment is the lack of control on authorities, i.e. subject authority control. The present research aims at examining the feasibility of subject authority control of Persian medical databases available on the Net. Based on research methodology, we have randomly chosen 50 keywords utilized by users searching databases for articles. In the pre-test stage, these keywords were searched through Iranmedex, a database for Persian medical articles. Comparing them with Persian medical thesaurus, those keywords exactly matched to the thesaurus words were entered in a designed database using Microsoft Access software. Then, we entered these authorized keywords in Iranmedex. Findings of new search sessions revealed that control of authorities on the one hand, makes information retrieval more precise and accurate and, on the other prevents false drops. The research findings can be used for modifying the process of information storage and retrieval on the Internet. The research concludes with a model for applying thesauruses as authority control tools for other databases available at Internet.