The complex biologic investigation of thyphoid fever is dictated by the necessity of instituting a pathogenetic therapy, especially in the toxic and complex forms. Performing 178 fuctional-metabolic tests in 50 cases of typhoid fever (of which 10 severe and complicated forms), the authors established the prognostic value energy deficiency (approximately P), lactate, alkaline reserve and GPT. Azotemia is only characteristic in the forms with renal involvement, and the other transaminases may be positive even whe the liver is not enlarged. In one case of repeated digestive hemorrhage no evidence could be found of the mechanism of consumption coagulopathy.