In recent years, the searching and indexing techniques for multimedia data are getting more attention in the area of multimedia databases. As many research works were done on the content-based retrieval of image and video data, less attention was received to the content-based retrieval of audio data. In this paper, we propose an approach to retrieve MP3 music objects based on their content. In our approach, the coefficients extracting from the output of the polyphase filters are used to compute the MP3 features for indexing the MP3 objects. We also propose an MP3 similarity measuring function to provide users the ability to approximately retrieve the desired MP3 objects. Experiments are performed and analyzed to show the efficiency and the effectiveness of the proposed method. Keywords music databases, MP3 databases, MP3 indexing, content-based music data retrieval, music feature extraction.