Image retrieval system is an effective and efficient tool for managing large image databases. A content based image retrieval system allows the user to present a query image in order to retrieve images stored in the database according to their similarity to the query image .In this paper content based image retrieval method is used as diagnosis aid in medical fields. The main objectives of this paper is to reduce the noise from an medical image with the use of Bayesian algorithm .Various algorithm are define in CBIR but we can use Bayesian algorithm to reduce the noise from an image . Bayesian algorithm provide the feedback and improve the performance of an image retrieval by using the resultant MSE(mean square error) and PSNR(peak signal to noise ratio).