A support apparatus (10) for supporting a trocar (12) while the trocar (12) extends through a body wall of a patient includes an inflatable collar (15) extending around the trocar (12) which can be inflated to a predetermined size by a source of fluid (17), where the source of fluid (17) is located on the trocar support apparatus 810) itself so as to be carried thereby and is defined by a pump (17) mechanism to provide a fixed volume allowing inflation only to a fixed size. An abutment member (14) is shaped to be received on an outer surface of a trocar sleeve (11) and adjustable longitudinally of the trocar sleeve (11) so as to be located at a selected position. A tube (16) connecting the pump (17) on the abutment (14) to the inflatable collar (15) is wrapped helically around the sleeve (11) of the trocar. The collar (15) includes a sleeve portion (15A) which can be unrolled on to the trocar sleeve (11).