Introduction: the mechanism of action of ultradiluted medicines has not yet been established[1,3]. Many basic research studies have focused on isopathic models using in vitro or in vivo designs [4,5]. Recent studies indicate that an ultradiluted (isopathic) antigen can transfer signals to the immune system and modulate its response when an organism is challenged against this same antigen [6]. Some studies on experimental infection of mice by T. cruzi identified apoptotic cells and showed that the increase of their number is associated with an increase also in the number of parasites in the blood of the infected animals, while blockage of apoptosis can be the target of therapeutic intervention [7,8]. Aim: to evaluate the development of apoptosis in mice treated with biotherapic of Trypanosoma cruzi in dilution 17d through in situ detection of fragmented DNA. Method: in a blind randomized controlled trial, 36 male Swiss mice age 4 or 8 weeks were distributed in groups control - treated with 7% hydroalcoholic solution(CI-4=9 animals or CI-8=9 animals); and treated with biotherapic 17d (BIOT-4=9 animals or BIOT-8=9 animals). Infection was performed with 1,400 trypomastigotes T. cruzi-strain Y via intraperitoneal. Biotherapic 17d was prepared through the addition of 0.9ml of concentrated T. cruzi (10E+7 trypomastigotes/ml) to 9.1 ml of distilled water. The following dilutions were prepared in 86% hydroalcoholic solution until dilution 16d. Dilution 17d was prepared with 7% hydroalcoholic solution. It was performed microbiological control and biological risk in vivo. Treatment: 0.2 ml in 3 consecutive days, oral route, from the moment infection was verified. Animals were sacrificed on the 3rd day of treatment in a chamber saturated with ether. The liver and spleen were removed and fixated in 4% paraformaldehyde for 24 hours and then included in paraffin. Apoptosis was evaluated through DNA fragmentation – TUNEL technique (TdT dUTP-biotin Nick End Labeling (ApopTag® Peroxidade-Chemicon). For statistical analysis software Statistica 8.0 was used. This study was approved by the Ethics Committee for Animal Experimentation of UEM. Results and Discussion: in the samples of liver of animals age 4 and 8 weeks either treated or not with biotherapic 17d it was found cells parasitized by amastigotes of T. cruzi with apoptotic bodies, or phagocytic cells with phagocytic vacuole with apoptotic marked material inside them. The number of cells in apoptosis in animals age 4 weeks was not significantly (p=0.03) larger in treated group BIOT-C4 than in control group CI-4 (Figure 1). In animals age 8 weeks, the number of cells in apoptosis was significantly (p

Introduction: about 10 million people worldwide suffer from Chagas’ disease [1]. The World Health Organization (WHO) has explicitly acknowledged the significance of this condition and supports the use of Complementary and Alternative Medicine by health systems integrated with conventional treatments. Even so, one century after its discovery it still represents a global challenge [1,2]. Biotherapics are ultradiluted medicines and the infection of mice by Trypanosoma cruzi is an excellent model to understand their effect [3,4]. At 8 weeks, mice are physiologically more developed than at age 4 weeks, including a more competent immune system [5]. Aim: the aim of this study was to assess the effect of biotherapic of T. cruzi in dilution 17x on liver and spleen tissue of mice of different ages infected by this protozoon. Method: in a blind, randomized controlled trial 12 male Swiss mice aged 4 and 8 weeks, infected by 1,400 blood trypomastigotes T. cruzi Y strain were divided into groups control – treated with 7% hydroalcoholic solution (CI-4=3 animals or CI-8=3 animals) and treated with biotherapic 17x (BIOT-4=3 animals or BIOT-8=8 animals). Treatment (0.2 ml biotherapic/day/animal, per gavage) started after infection was verified (4th day) and animals were sacrificed on the 3rd day of treatment. For histopathological exam, the liver and spleen were removed and fixated in 4% paraformaldehyde for 24 hours and then processed for inclusion in paraffin. Semi-serial 7mm cuts were made and subjected to hematoxylin-eosin stain. It was performed a quantitative analysis of the number of nests of amastigotes and inflammatory foci in the liver. Slides were observed under microscope Olympus BX41 (Tokyo, Japan) and images captured with camera Qcolor3 (Olympus) coupled to the microscope. In the spleen it was counted the number of nests of amastigotes and the number of foreign-body giant cells. In each organ, 20 microscopic fields/cut were counted under power 40x totaling 120 fields/animal with microscope Olympus CBA (Tokyo, Japan). To analyze data it was used software Statistica 8.0. For data not exhibiting normal distribution it was used Kruskal-Wallis’ test at 5% significance and ANOVA for the ones with normal distribution. Chi-square test was used to compare percentages. Biotherapic 17d was prepared by adding 0.9 ml of blood with T. cruzi (10E+7 trypomastigotes/ml) to 9.1 ml of distilled water in laminar flow. Following dilutions were prepared in 86% hydroalcoholic solutions up to 16x. Dilution 17x was prepared with 7% hydroalcoholic solution [6]. It was performed microbiological control and in vivo biological risk of the biotherapic. Results showed a number of colony forming units proper for use (>1CFU/ml). Intraperitoenal inoculation of the biotherapic did not cause infection in animals. This study was approved by the Ethics Committee for Animal Experimentation/UEM protocol 030/2008. Results and Discussion: in the liver, animals of group BIOT-8 exhibited less nests of amastigotes (p