This thesis explores further the drug release from hydrophilic matrices in three parts by means of dissolution in paddle apparatus, using matrices with different shapes such as the dome shape, cylindrical shape, matrices with one base flat and the other concave and matrices with one base flat and the other convex. The first part involves surface area increase of the “dome” matrix during the process of swelling. The swelling area of single dome and cylindrical matrices, partially coated with an impermeable film, was calculated during dissolution experiments. In the second part of this work the release patterns of the dome and cylindrical hydrophilic matrices were compared to matrices of the same shape containing a non-swelling polymer. In the third part a new method of assembling dome matrices units by the use of ultrasound was explored. Drug release kinetics and mechanisms were studied for all the different matrices prepared, applying the Ritger-Peppas equation An approximation of the swollen surface area of the hydrophilic matrices was found. It was in addition found that the shape of the matrices used in these experiments did not significantly affect the release mechanisms, but the release patterns were slightly changed. Neither did the assembly of the dome matrices affect the release mechanisms, but gave a modified release pattern.