A study of acute gastroenteritis in soldiers was carried out during a 1-year period. Causes of diarrhea were compared between 33 soldiers stationed in southern Lebanon and 174 soldiers stationed in northern Israel. Shigella sp. caused 42.4% of diarrheal disease in Lebanon, compared with only 19.0% of cases in Israel. Sh. flexneri was a more common cause of bacillary dysentery in Lebanon than in Israel (71.4 vs. 18.2%, respectively), and caused a more severe illness.