Open Grid Service Architecture - Data Access and Integration (OGSA-DAI) is a middleware which aims to provide a unique interface to heterogeneous database management systems and to special type of files like SwissProt files. It could become a vital tool for data integration in life sciences since the data is produced by different sources and residing in different data management systems. With it, users will have more flexibility in accessing the data than using static interfaces of Web Services. OGSA-DAI was tested to determine in which way it could be used efficiently in a Grid application called RNAi screening. It was evaluated in accessing data from bio-databases using the queries that a potential user of RNAi screening would execute. The observations show that OGSA-DAI has some considerable overhead compared to a JDBC connection but provides additional features like security which in turn are very important for distributed processing in life sciences.