Sustained release systems in the forms of chitosan (CTS) tablet and extrude for releasing amoxicillin were studied. The degradation of amoxicillin in pH 1.2 was determined. The effects of particle sizes of chitosan on the dissolution profiles were investigated. The result showed that chitosan with the particle size less than 75 ${mu}$m yielded the best controlled release pattern and it was comparable to that was obtained from the hydroxypropylmethylcellulose (HPMC) tablets. Moreover, the tablets containing chitosan with particle size less than 75 ${mu}$m were able to provide a significantly improved sustained release profile of amoxicillin compared to the release profile of a commercial capsule. All release profiles of amoxicillin from the chitosan tablets could be described by first-order kinetics.