Two (8, 9)opogytricyclo[5.2.1.0^2,6]dec-3-enes were prepared from endoand ego-tricyclo [5.2.1.0^2,6] dec-3, 8-diene by partial epoxidation.Further epoxidation was carried out separately by oxidation with peracetic acid or by addition with hypoohlorite followed by elimination of hydrogen chloride.Thus four stereoisomers of (3, 4),(8, 9)diepogytrieyclo[5.2.1.0^2,6] decane were obtained.Their configurations were discussed.