The liberation of phenylbutazone from tablets prepared by wet granulation was examined. It was found that the solution process can be described by the equation c = cs (l-e-K.t alpha). The influence of the binder concentration and the disintegrant on the liberation rate was also studied. The increase of the Klucel MF concentration accelerated the liberation of the agents. Among the disintegrants Polyplasdone XL and cyclodextrin block polymer turned out to be very good.