Three liquid nutrient media (phosphate buffer medium, 1% buffered peptone water pH 7.6-7.7, buffer casein yeast medium) and live solid media (Endo's, Serov's, and differential diagnostic medium with bromothymol blue, made in this country, and two foreign ones, agar deoxycholate and McConkie's) are compared in examinations of the material from 213 patients with acute intestinal diseases and from 460 small mammals. The results demonstrate a higher efficacy of bacteriologic investigations carried out in the new buffer casein yeast medium or 1% buffered peptone water, pH 7.6-7.8. The data are also indicative of the essential advantages of the differential diagnostic medium with bromothymol blue and prompt its wide practical use.