Maleate-denatured poly(vinyl alcohol) (M-PVA) was crosslinked with heating. The mechanism of crosslinking was studied with several procedures: titration, Fourier transform infrared, and solubility. The carboxyl groups of M-PVA consisted of carboxylates and a few free carboxyl groups. The crosslink was the ester linkage between hydroxyl and carboxyl groups. Several kinds of M-PVA tablets were prepared under different conditions: pressures of 200-600 kgf/cm(2) and grain sizes of 75 (pass) to 250 Am (on). The swelling behavior of these chemically crosslinked tablets was studied in a buffer solution of pH 7.4, mainly at 37degreesC. Moreover, the effect of temperature from 5 to 50degreesC and the effect of repeated swell-dry cycles on the behavior of the tablets in a buffer solution [106 mum (on), 200 kgf/cm(2)] were studied. The release of p-acetamidophenol from those tablets in the pH 7.4 buffer solution was studied. The different release patterns were due to the differences in the swelling behavior.