Creep in metal alloys is an important failure mode for high temperature and stress applications, but despite extensive study it is still not fully understood, particularly the early stage of creep cavity formation. This paper describes a novel constant load cantilever beam test to investigate creep damage and cavitation at grain boundaries in copper bicrystals. Bicrystals of copper have been prepared with the grain boundary oriented normal to the beam long axis, allowing the development of damage at a single boundary to be studied. Tests were conducted at a temperature of 285° C in a vacuum of 10-10 MPa. Creep cavitation is observed in copper bicrystals of {001} and {111} orientation with a 22° rotation at the boundary. We compare these data with observations for a polycrystalline copper specimen.