A pole top extension assembly (10) for mounting a wooden extension bayonet (37) having a rectangular cross section to the flattened top of a cylindrical wooden utility pole (21). The pole top extension assembly (10) comprising a pair of bracket members (25 and 27) each having leg portions (30) extending downwardly from the top of he wooden utility pole (21), and each bracket member further having a matingly interengageable portion (29 and 31) which couples the said bracket members together over the top of pole (21). At least one of said bracket members including a rectangular collar (35) opening upwardly to receive a bayonet member therein, with said rectangular collar having two pairs of opposite side walls (41and 43) oriented, respectively, substantially parallel and perpendicular to said leg portions (30).