The various instruments described in this text all provide an integrated and automated approach for separating free and bound ligands along with other steps in radioimmunoassay. Although the various systems differ significantly in design, they all perform these basic manoeuvres, for the most part, without any operator intervention. It is hoped that the following descriptions of the various system capabilities will not only provide useful information for present and potential users of the systems, but also stimulate additional development by manufacturers which will bring the full potential of radioimmunoassay even closer to a reality.