Metasearch engines submit the user query to several underlying search engines and then merge their retrieved results to generate a single list that is more effective to the users' information needs. According to the idea behind metasearch engines, it seems that merging the results retrieved from different retrieval models will improve the search coverage and precision. In this study, we have investigated the effect of fusion of different retrieval techniques on the performance of Persian retrieval. We use an extension of Ordered Weighted Average (OWA) operator called IOWA and a weighting schema, NOWA for merging the results. Our experimental results show that merging by OWA operators produces better precision. Categories and Subject Descriptors Information Search and Retrieval, Retrieval Models. Keywords Information Retrieval, Information Fusion, Persian Text Retrieval.