The roles of olfaction and vision in the homing behaviour and orientation to a home site in Ulvaria subbifurcata were investigated. These were examined by studying the home-site fidelity and the homing performance of normal, blind, and anosmic fish and the orientation to the home site of normal and sensory-impaired fish. The orientation and homing experiments indicated that olfactory contact with the home site is involved in the steering mechanism in homing. The home-site fidelity of anosmic fish, and the fact that some anosmic fish homed, indicated that vision may also be involved in the recognition of a restricted area around the home site.