Radial counter-immunoelectrophoresis was evaluated with sera from surgically-confirmed hydatidosis cases, patients with other parasitic diseases and healthy controls. Radial counter-immunoelectrophoresis was a sensitive as classic counter-immunoelectrophoresis based on the same positivity criterion and was equally specific for the immunodiagnosis of human hydatidosis. The procedure appears to be simple and rapid (the immunoprecipitation step requires just 5 minutes) and merits consideration.