In this panoramic study about the acute phase of schistosomiasis mansoni the author describe its clinical picture and diagnosis, the complementary tests, the author describes its clinical picture and diagnosis, the complementary tests, ical pictures of the incubation, fastigium and suppression periods are described. The diagnosis of the acute phase is based on epidemiologic data are often positive, there being mention to an infective bath, usually 30 to 40 days prior to the onset of the disease. Fever (38-40°C) is noticed at the physical examination, as well as prostation and microlymphadenopathy. Enlargement and tenderness of the liver are found in 95 percent and splenomegaly in 70 per cent of the cases. The most important laboratory tests for the diagnosis are: repeated direct examination in stool specimens for the detection of viable S. mansoni eggs, and repeated leukocyte count that generally shows leukocytosis and eosinophilia. When in doubt or for diagnostic complementary one may always recourse to the rectal endoscopy, the ocgrama and the liver biopsy. The endoscopy usually reveals hyperemic, edematous, friable and granulous mucosa with bleeding points. The needle-biopsy of the liver followed by the histopathologic examination of the hepatic tissue discloses granulomas in the necrotic-exudative phase, among other findings. The differential diagnosis must be made with diseases as follows: gastroenteritis, typhoid fever, bacilar disentery, acute amebiasis, and prolonged septicaemic salmonellosis, although one should also include miliary tuberculosis, acute abdomen, acute glomerulonephritis, infectious mononucleosis, leptospirosis, hepatics and polyneuritis. Treatment is established on general measures, corticotherapy, and specific therapy. The corticosteroids ( prednisone ) should be administered during approximately 7 to 10 days; this therapy leads to a dramatic regression of the toxic-infectious picture in the first 24-48 hours. The specific therapy mitrothiazole derivative = Ambilhar and hydroximethylic derivative of Miracil D = hycanthone) is employed after the regression of the toxic-infections picture or in the frank acute phase; in this case, the disappearance of the general symptoms and the intestinal disturbances occurs from the fifth day of therapy on. When either Ambilhar or hycanthone is used in just one therapeutic schema, complete cure is observed in 40 per cent of the cases; this rate goes as high as 80-90 per cent when specific medication is repeated after the occurrence of relapse. Finally the author points out some evolutionary aspects of the disease, mainly its evolution from acute Lo hepatosplenic schistosomiasis, and to cor pulmonale