An adapter assembly for a flexible circular stapler including a pusher assembly, a trocar assembly, a first drive assembly and a second drive assembly. The pusher assembly includes a pusher member, a puller member, and first and second pulley members. The trocar assembly includes a trocar member operably disposed relative to the pusher assembly. The first drive assembly includes a first cable for advancing and retracting the trocar member relative to the pusher assembly, and the second drive assembly includes a second cable for retracting the puller member to cause rotation of the first and second pulley members. Rotation of the first and second pulley members causes advancement of the pusher member.