Kanendomycin (KDM), a newly developed broad spectrum antibiotic obtained from a mutant strain of streptomyces kanamyceticus, is known to be equal or in some cases superior to KM in antibacterial activity except mycobacterium tuberculosis. However, in the field of acute diarrhea' diseases, experiences with it have so far been not so many that its clinical value remains yet to be determined.In this situation, the author, a member of a special study team on KDM, presented in this paper the results of its trials on acute dysenteric patients.Among patients who were admitted to Tokyo Municipal Ebara Hospital during Oct., 1968-Mar., 1969 under the diagnosis of bacillary dysentery, a total 35 patients were employed, the breakdown being symptomatic shigella (B or D) positive adults (12) and infants (3), symptomatic shigella negative adults (6), adult carriers (8), symptomatic shigella (B or D) positive infants (4) and diarrheal adults with pathogenic coli (1) and staphylococcus (1). Most strains from 27 shigella positive cases were shown as resistant to CP, TC and SM but sensitive to KM, AB-PC and NA except for 5 strains which were sensitive to all drugs tested. Period of the medication was. 5 days in all and dosis was daily 2.0g orally in adults and 1.0-2.0g orally in infants every 6 hours 4 times a day.The followings are the results:1) In point of stool findings and frequency, about 80% of symptomatic patients were effectively treated, excellent ones (normalized within 3rd medication day) being 4 and good ones (within 5th day) being 13. Mean number of days needed for stool frequency normalization was 2.9 in infants, 3.1 in shigella positive adults, 3.5 shigella negative adults and 4.5 in pathogenic coli and staphylococcus cases.2) Eradications of causative agents were seen by 2nd day in about half of the cases. However, those who needed 3-5 days were not so rare. Ineffective cases, i.e. requiring more than 6 days, were 20% in adults and 43% in infants.3) Twenty seven cases of them were observed by rectoscopy twice in the course of hospitalization; 1st, prior to the medication, 2nd, 2weeks after the end of medication. Seventy four percent were recognized overtly as having ulcers at 1st test. On the other hand, 78% were confirmed as completely cured at 2nd test. The records can be regarded fairly satisfactory.4) As to the dosis-clinical effects relationship, the impression is that 30-40 mg/Kg was reasonable in adults, but in infants somewhat greater dosis (60-70 mg/Kg) seemed necessary.5) Side effects were almost negligible.6) Maximum serum concentration of the drug was 1-2 mcg/ml after 1 g administration. It means it is poorly absorbable from the intestine.In the previous report (Vol.43, No.1, in this journal), the author favored the combination of easily and poorly absorbable antibiotics in this field, this time too he would like to state the same, e.g. the combination with AB-PC as idealized medication.