Matrix tablets were prepared using blends of xanthan gum (XG) and ethylcellulose (EC). Metronidazole was used as a model drug. The ability of the prepared matrices to retard drug release in the upper gastrointestinal tract (GIT) and to undergo enzymatic hydrolysis by the colonic bacteria was evaluated. For this, drug release studies were carried out in the presence and absence of rat cecal content. The overall rate of release of metronidazole from ethylcellulose matrices was significantly higher than from Xanthan gum matrices. These results indicate that XG has higher drug retarding ability than ethylcellulose. Formulations of the model drugs containing 40 % of XG followed zero order kinetics via anomalous or non-fickian release mechanism whereas that containing 30 % XG followed first order kinetics via fickian diffusion. Formulations containing mixture of polymers followed higuchi kinetics via fickian diffusion. Presence of XG alone or in combination retarded the initial release of drugs from the tablets due to high swelling, which made them more vulnerable to digestion by the microbial enzymes in the colon. Optimum release was observed with metronidazole formulation containing XG alone (formulations containing Xanthan gum 30% and XG 40 % respectively) and in combination (formulation containing XG 22.5%:EC 7.5 %) Significance difference was observed between drug release in dissolution medium with and without rat cecal contents for the optimum batches of metronidazole tablets (P<0.05).