Tablets containing paracetamol were prepared by wet granulation. The model drug, paracetamol (API) and the diluent, milled isomalt (IM) were applied in different ratios where the granulation liquid was kept constant in each sample. The purpose of the study was to investigate the effect of wet granulation with milled isomalt on the tabletting properties of poorly compressible paracetamol. The results of tabletting process and the tablet characteristics were evaluated with 3(2) type face-centered full factorial design. The API: IM ratio (X-1) and compression force (X-2) were selected as independent variables. The dependent variables were as follows: the parameters of the tabletting process - lubrication coefficient (R-value), relative elasticity, friction work - and characteristics of the dosage form such as tablet hardness, friability, disintegration time, tensile strength. The results indicated that milled isomalt has an advantageous effect on both the process of compression and the tablet characteristics due to its binder properties. Furthermore an optimal composition of the API and the diluent is to be found according to the compression process and the dosage form. (C) 2010 Elsevier B.V. All rights reserved.