In an outbreak of shigellosis in a kibbutz in Northeastern Israel, oral nalidixic acid failed clinically in 35% and microbiologically in 28.4% of 14 children as compared with no clinical and microbiologic failure in 25 children who were treated with oral azithromycin (P < 0.01 and 0.012, respectively). Thus azithromycin could be a suitable alternative to nalidixic acid.