Matrix tablets containing carvedilol phosphate were prepared using 27 formulations in three batch series where different ratios of K4M CR and K15M CR were used as release retarding agents. Avicel PH 101, Starch 1500 and Lactose monohydrate were used as diluents in the formulation of three batches. The data were subjected to different models in order to evaluate their release kinetics and mechanisms. Tablets in case of all formulations showed more than 50% of drug release in 12 h when Methocel K4M CR and K15M CR constituted 18% and 15% of the matrix respectively. It was found that Avicel PH 101 decreases while Starch 1500 and Lactose monohydrate increases drug release.