The author presents six cases of mansonic Schistosomiasis observed during toxemic stage. Of these, one was a woman whose symptomatology was of one year's duration. She conceived and gave birth to an alive child during the illness. She presented signs of hepatic fibrosis at the time of first examination, while she was still in the acute phase of the illness. All these patients presented fever, abdominal pain, hepatosplenomegaly and other manifestations which have been described, in this period of the parasitosis. As predominant findings in the leucogram were leucocitosis with eosinophilia as occurs in helmintiasís with a tissue phase. Nor all the patients presented anemia. In addition to the alterations in the serum proteins and results of the liver function studies the author points out the hypoglycemia and hypocholesterolemia found in some of the cases. Worthy of note was the late appearance of a positive intradermic skin test for the diagnosis of schistosomiasis. All the patients were submitted to antimonial treatment, with good results. As side reaction were noticed exacerbation of fever, leading at times to the interruption of the treatment. The author refers to other treatments used in the Orient, the F 30.066, an oral nitrofuran derivative, and seeds of Cucurbita moshata. He suggests animal and human investigations with pumpkin seeds, formerly used as a taeniafuge.