Abstract: A machine for transferring liquids to and from the wells of assay trays in a controlled, automated manner and a solid phase assay tray for use with the machine. The machine includes a horizontally translatable table (15) that holds the tray (46), a plurality of liquid dispensing manifolds (54) for dispensing liquids into the tray wells (50) and an aspirating manifold (65) for aspirating liquid from the well. The dispensing and aspirating manifolds are mounted on a vertically translatable head (16) above the table. Each dispensing manifold is equipped with a row of dispensing tubes (56) and is connected via a pump (58) to a liquid container (62). The aspirating manifold is equipped with a row of aspirating tube (66) and is connected via a pump (69) to a waste liquid receptacle (73). A microprocessor (85) controls the movements of the table and manifolds and operates the pumps.