Diabetes has become a common disease today. It is based on the assumption that a person is diagnosed as having diabetes by trying to guess in a computer based on various parameters. The parameters used in the estimation were determined by the National Institute of Diabetes and Digestive and Kidney Diseases in 1990, Pima Indians Diabets Databes' database of diabetes disease was created. Data set containing 8 qualities and 768 samples were obtained in the database. Data were classified using the Decision Trees (DT) and Bayes Classification methods in the Weka environment using the data set.