Application of NMR tomography in survey of oral forms of modified release drugs. The aim of the survey was to evaluate the behavior of modified release tablets in water medium of artificial digestive acid in a non-invasive way. NMR microtomography was employed to measure the changes in structcure and size of tablets over time. Changes in volume and size of these tablets were compared to the release of active agent in five series of tablets: one floatation and four advesive tablets series. These comparisons shown that relationship between its size and its active agents release occurs in dependance to the tabletís structure.