The author makes an introduction about the techniques used in the Country for the complete reaction of complement fixation in Chagas disease and suggests the use of the technique of 50% of hemolisis of Wadsworth used in the serological diagnosis of the Chagas disease by Pedreira de Freitas. Information is given for the first time in the country on the use of this technique with 201 serums of the vereda of Pizarreal, Norte de Santander, Colombia, with positive coefficient of 26.81%.