A surgical device is provided for use in joining a first tissue layer forming a first hollow region and a second tissue layer forming a wall of a second hollow region, to produce an anastomosis. The device comprises a needle capable of passing from the first region to the second region by penetrating the tissue layers, a tag removably carried by the needle, the tag having a trailing portion, and means for separating the tag from the needle after the needle has penetrated both layers, to leave the tag in the second hollow region, but with the trailing portion extending into the first hollow region. Anastomosis forming articles are described which comprise a pair of components for compressing the tissue layers between them.