A gastroenteritis outbreak of Shigella sonnei involving 122 children occurred between April 2001 and January 2002 in I-lan, Taiwan. The resistant rates of the isolates to nalidixic acid, trimethoprim-sulfamethoxazole, ampicillin and ceftriaxone were 98, 97.5, 32 and 27%, respectively. None of the isolates was resistant to ciprofloxacin. Prolonged bacterial shedding in the feces can occur when an inappropriate antibiotic is used.