Sixty-eight strains of multi-drug resistant Shigella dysenteriae type 1 were isolated from outbreaks of severe dysentery in three areas of Kenya, namely, Kisumu, Mombassa and Nairobi. The strains were tested for their susceptibility to seven antibiotics. Plasmids were extracted to study their variety and conjugated with Escherichia coli K12 to identify the plasmid coding for the resistance gese. All the strains were resistant to ampicillin, trimethoprim-sulfamethoxazole (S-T), tetracyciine and chloramphenicol. They were sensitive to gentamicin, kanamycin and nalidixic acid. Part of the resistance was found to be plasmid mediated and the sizes of plasmids coding resistance gene wereSMDaand 19MDa. These piasmids coded resistance for ampicillin, trimethoprim-sulfamethoxazole, tetracyciine and chloramphenicol. Verotoxin (VT) production was demonstrated in 80% of the strains by oligonucleotide DNA-DNA gybridization of whole cells with the VT-probe. In view of the extent of drug resistance exhibited by Shigella dysenteriae Type 1 in this study, we recommend the use of nalidixic acid as a first choice of treatment in multiresistant S. dysenteriae Type 1 dysentery outbreaks. Compared to the other two agents that the pathogen was sensitive to, nalidixic acid is relatively cheap with the cost of 7 days treatment for an adult being approximately five US dollars. Resistance to nalidixic acid has to be, however, closely monitored as S. dysenteriae Type 1 has been reported to develop resistance to this drug over time.