The aim of this study was to assess both dissolution and release profile of sodium alendronate (AL) from hydrophilic matrix tablets based on different sorts of carbopol with or without chitosan or trimethyl chitosan. There have been prepared three formulations (F1-F3) by direct compression for matrix tablets using as hydrophilic polymer matrix forming 15% Carbopol 71 (C 71), Carbopol 971 (C 971) or Carbopol 974 (C 974). In parallel, there were prepared two series of three formulations where carbopol has been associated with chitosan (CHT) (F4-F6) or trimethyl chitosan (TMC) (F7-F9). Research results have shown that the introduction of C 974 in the formulation, a highly cross-linked polymer, determined a decrease in the release rate without altering the AL general dissolution and release profile, according to the value of the similarity factor f2. The formulations with TMC or CHT have shown superior release properties of AL compared with the formulations F1-F3, having also a different release profile according to the difference factor f 1 and the similarity factor f2. Results from data fitting at three mathematical models: zero order, Higuchi model and Korsmeyer-Peppas model, revealed that the introduction of CHT and TMC into the hydrophilic matrix tablets based on carbopol determines AL release by a process of diffusion based on Fick's law.