Un total de cinco pacientes con diagnostico de sindrome miastenico de Lambert-Eaton fueros estudiados utilizando tecnicas electrofisiologicas. Los resultados presentados en este articulo demuestran que la patogenia del sindrome de LEMS es producida por un mecanismo autoinmune, que afecta la sinapsis neuromuscular, bloqueando a traves de anticuerpos subunidades de los canales ionicos terminales axonales para el Ca2+ y alterando los mecanismos basicos de recaptacion de Ach a nivel de receptores presinapticos. Rev.cienc.biomed. 2010, 1(1): 128-135 . PALABRAS CLAVES Sindrome de Lambert-Eaton. Canales de calcio. Receptores presinapticos. SUMMARY Five patients with the diagnosis of Lambert-Eaton syndrome were studied using electrophysiological techniques. The results present in this paper demonstrated that the physiopathology of LEMS is produced by an autoimmune mechanism that impair presynaptic release of acetylcholine. Antibodies against calcium channels and presynaptic receptors have o role in the presynantic physiopathology of this disorder. KEYWORDS Lambert-Eaton syndrome. Calcio channels. Presynaptic receptors.