Only ninety-three strains of Shigella, eightyseven of which have been identified as S. sonnei and six as S. flexneri were collected during 1969-1976 at the Pathogen Enterobacteria Centre of Pisa in Central Italy, as evidence of an epidemiological situation marked by a rare occurrence of syndromes related to these organisms. The collected strains were tested with disks of nine antibacterial drugs in common use: the survey detected sensitivity of all the strains to cephaloridine, ampicillin, carbenicillin, kanamycin and gentamicin, whereas a fair percentage of resistance appeared to streptomycin, tetracycline, chloramphenicol and cotrimoxazole. Both within multiresistant strains and those characterized by single resistances (forty-three of them in all), were present strains capable of transferring different drug resistance patterns to E. coli K-12, as evidence of being under extrachromosomial genetic control.