Abstract: Degassing apparatus for removing entrained gas bubbles from drilling fluid comprises a conduit through which drilling fluid may flow and a cavitator located within the conduit. The conduit includes generally opposed first and second surfaces positioned to contact drilling fluid flowing through the conduit. The cavitator has first and second surfaces respectively opposed to the conduit first and second surfaces and is reciprocatable between a first position proximal the conduit first surface and a second position distal the conduit first surface and proximal the conduit second surface. In operation, drilling fluid is conducted through the conduit, and the action of the cavitator alternately compresses and then rarefies the fluid between the cavitator surfaces and the respective opposed conduit surfaces.