Nowadays, there is a huge amount of data being collected, especially at the age of internet. It is very hard to extract knowledge from this huge amount of data. These data are of no use unless we retrieve knowledge from it. As there is a huge raise in in the volume of data, it is an obvious challenge to reduce the data set and extract useful information from it. This paper mainly focuses on extracting knowledge in the form of rules using rough set by finding the reduced set of data. In rough set theory, the data is represented in the form information system. Discernability matrix is used to find the core and reduct of the attribute. After finding the core and reduct the strength of the attributes is found and the rules are generated. Also the proposed work is validated by taking real time example which extracts knowledge in the form of rules. © Research India Publications.