FIAX TM.(flouroimmunoassay) was first used with success in detection of antibodies against T.lewisihomogenates.These antibodies were present in serum of infected rats in a high level after two weeks from infection and in a lower level after six weeks .These antibodies are specific against .T.lewisi and not present in uninfected rats .The test is easy ,rapid and specific, we hope to apply it in human cases of trypansomiasis