An inclusion complex of phenytoin (PT) with β-cyclodextrin (β-CyD) in molar ratio of 1:1 was prepared, and the interaction between host and guest molecules was confirmed by infrared spectrometry, differential scanning calorimetry and X-ray diffractometry. Suppositories were prepared by the fusion method. PT and PT-β-CyD complex were added to PEG 1540 and Witepsol H-15 under the vigorous stirring at 40℃. Content uniformity was tested for different formulations of the PT suppositories. The release rates were dependent on the K.P. V dissolution apparatus and the dialyzing tubing method. Then, the release rates were increased in the following order: PT-β-CyD complex in PEG 1540 > PT in PEG 1540 > PT-β-CyD complex in Witepsol H-15>PT in Witepsol H-15. The area under the curve and maximum blood concentration after rectal administration were increased in the following order: PT-β-CyD complex in PEG 1540>PT in PEG 1540>PT-β-CyD complex in Witepsol H-15>PT in Witepsol-15.