Omeprazole(OMP) complexes such as inclusion complexes of OMP with $hydroxypropyl-{eta}-cyclodextrin$(HPCD) and ${eta}-cyclodextrin({eta}-CD)$, OMP-cholestyramine(CHL) and OMP-ethylenediamine(OMP-ED) were prepared, respectively. The partition coefficients in Witepsol H-15 /pH 7.4 phosphate buffer solution of OMP complexes$(OMP-HPCD;;3.69{pm}0.26,;OMP-{eta}-CD;;4.08{pm}0.21,;OMP-CHL;;4.36{pm}0.25;and;omeprazole;sodium(OMP-Na);;3.64{pm}0.37)$ were higher than that of OMP $(2.66{pm}0.47)$. OMP was not completely dissolved until even 3 hrs, but all the OMP complexes studied were released about 100% in 20 min. The rectal suppositories containing OMP or each above OMP complex were prepared using Witepsol H-15 base, and their dissolution and stability were examined, and pharmacokinetic study were investigated after their rectal administrations to the rabbits. While the suppository containing OMP was released only less than 60% in 150 min, $OMP-{eta}-CD$, OMP-CHL, OMP-Na and OMP-ED suppositories were all released about 65% in 20 min. Especially, OMP-HPCD suppository released OMP about 70% in 10 min. All the additives such as sodium laurylsulfate, eglumine, arginine and PVP increased drug release from OMP-HPCD suppository to some extent. The decomposition rate constants of OMP in the suppositories were $9.117{ imes}10^{-3};day^{-l}$ for OMP suppository, $2.121{ imes}10^{-2}$ for OMP-HPCD, $1.607{ imes}10^{-2}$ for $OMP-{eta}-CD$, $9.26{ imes}10^{-3}$ for OMP-Na, $6.769{ imes}10^{-3}$ for OMP-CHL and $5.58{ imes}10^{-3};day^{-l}$ for OMP-ED suppository, respectively. Additives such as arginine, eglumine and ED had some stabilizing effect for OMP-HPCD, OMP-CHL and OMP-Na suppositories, respectively. After 6 month-storage at $30^{circ}C$, 75% RH, OMP-CHL suppository was most stable. The values of Tmax for OMP-HPCD and OMP-Na suppositories were $11.7{pm}2.36;and;11.4{pm}2.56;min$, respectively. The values of Cmax for OMP-HPCD and OMP-CHL suppository were $2.31;{mu}g/ml;(p<0.01);and;1.89;{mu}g/ml;p<0.01)$, respectively. The values of AUC for OMP and $OMP-{eta}-CD$ suppository were $61.9{pm}25.79;and;68.6{pm}29.48;{mu}g;{cdot};min/ml$, and the corresponding values for OMP-HPCD and OMP-CHL were $106.1{pm}43.16;(p<0.05);and;127.3{pm}42.52;{mu}g;{cdot};min/ml(p<0.01)$, respectively. The above results indicate the OMP-HPCD and OMP-CHL suppositories have the excellent bioavailabilties in vivo study.