Shigella species have been one of the most common causes of acute diarrhea in Bangkok, Thailand. The incidence of shigellosis increased steadily from 1984 to 1988. The majority of Shigella species isolated from specimens from patients with acute diarrhea in Bangkok in 1988 were resistant to both ampicillin and trimethoprim-sulfamethoxazole (TMP-SMZ). Shigella flexneri was the most commonly isolated organism and had the highest rate of resistance to ampicillin, chloramphenicol, TMP-SMZ, and tetracycline. The antimicrobial agents of choice for the treatment of shigellosis have been changed from ampicillin to TMP-SMZ and recently to the fluoroquinolones. We conducted a controlled study of norfloxacin that revealed its efficacy for eradication of Shigella species from the stool of both adults and children. The fluoroquinolones shorten the course of diarrhea, reduce the shedding of the organism, and prevent the spread of infection. No short-term adverse effects of the quinolones were observed in this study; however, its use among children should be restricted to treatment of severe shigellosis and the duration of treatment should be as short as possible.