Complexation of 5-amino salicylic acid (1), sulfasalazine (2) and diflunisal (3), nonsteroid anti-inflammatory drugs with a wide range of actions, with beta-cyclodextrin (beta CD) have been studied by means of differential scanning calorimetry and UV-vis spectroscopy. The experimental results have shown the formation of stable inclusion complexes. The molecular modeling study has been carried out to elucidate the different inclusion behaviors. A preliminary Monte Carlo (MC) conformational search of the guest molecules followed by docking and multiple minimization procedure with two force fields, AMBER* and PCFF, has indicated that drugs forms stable complexes with beta CD. The results are in good agreement with the experimental data from measurement of stability constants. (c) 2008 Elsevier B.V. All rights reserved.