The author states that, for about 18 years, he has attempted the therapeutica of Neotropic Exanthematic typhus in many years with no appreciable result. Now, however, he thinks the question is solved by the proper use of Terramycine. Before this antibiotic appeared he advised Aureomy of Terramycine. Before this antibiotic appeared he advised Aureomycine and Chloromicetine. He prefers, however, Terramycine, via the mouth, sub cutaneous or intra-muscular. The author says that with or without therapeutics 16 to 18 per cent of the serious cases of Neotropic Exanthematic Typhus in Brazil, recovered. For tis reason, bringing together about 34 cases of the serious forms of the disease, he resolved to publish the following table. Here we see that of the patients treated with Aureomycine, 31,25% died and of those treated with Teramycine, only 6,6%. It whould be noted that the Terramycine patient was in the Hospital Cícero Ferreira, only seven hours before he died. The author gives four clinical reports of the disease.