In this study, solid dispersions of poorly water-soluble Tibolone in a poly(ethylene glycol) matrix were prepared with conventional melt mixing and microwave irradiation. The results of the assay content, LC-MS, and (HNMR)-H-1 indicated that microwave irradiation did not affect drug stability when a relatively low irradiation power (440 W) was used. Fourier transform infrared spectroscopy indicated that there were no hydrogen bonds formed between Tibolone and poly(ethylene glycol), and this affected the drug's crystallinity and its particle size distribution. The dissolution rate of the drug was slightly higher in the case of dispersions prepared by microwave irradiation. This enhancement of the drug dissolution rate was probably due to the lower size of the Tibolone particles in the dispersions prepared by microwave irradiation. The application of microwaves represents a promising alternative to conventional preparative methods of drug dispersions. The main advantage in comparison with conventional melt mixing is that solid dispersions can be prepared in much shorter times. (C) 2008 Wiley Periodicals, Inc.