Inclusion complex of ibuprofen with $2-Hydroxypropyl-{eta}-cyclodextrin;(HP-{eta}-CD)$ in aqueous solution and in the solid state was evaluated by the solubility method and the instrumental analysis such as infrared spectroscopy, thermal analysis and x-ray diffractometry. The aqueous solubility of ibuprofen was increased linearly with the increase in the concentration of $HP-{eta}-CD$, showing an $A_L$ type phase solubility diagram. The results showed that the dissolution rate of ibuprofen was significantly increased by complexation with $HP-{eta}-CD$. $Ibuprofen-HP-{eta}-CD$ complex enhanced the mean plasma concentration levels and the area under plasma concentration-time curve after oral administration compared to those of the drug alone. It is concluded that the complex of ibuprofen with $HP-{eta}-CD$ increases the dissolution rate and improves the bioavailability of the ibuprofen by the formation of a water-soluble complex.