Abstract: A shaft sealing system for a steam turbine includes at the high-pressure inlet end an outer air seal (40 ) and an outer steam seal (42 ) each comprised of segmented circumferential seals and a plurality of labyrinth seals (44, 46, 48). The low-pressure end of the turbine is provided with a segmented circumferential seal (60) substantially precluding ingress of air past the seal. The steam leaking past the inner two labyrinth seals (46 and 48) is returned to a stage of the turbine by a first leak-off pipe system (50). Air leaking past the air seal and steam leaking outwardly past the outer steam seal (42) is piped to the main condenser (58). High-pressure steam between the outer steam seal (42) and the outermost labyrinth seal (44) is piped via a second leak-off path (56) to a turbine stage downstream from the first-mentioned turbine stage.