Diarrhea is still a major cause of morbidity and mortality among children in developing countries. The Bedouin population of southern Israel is in transition from a nomadic to a settled life-style. We examined maternal knowledge and reported behavior when their children had diarrhea. Mothers defined diarrhea as the passing of 4-5 stools per day. The most frequent signs of the illness were an increased number of watery stools with changes in either color or form. The most frequent symptom that prompted mothers to seek medical aid was blood in the stool. All mothers reported increasing fluid intake in their children during diarrhea, and most reported giving herbal tea. About half of the women avoided milk products and used special foods for the treatment of diarrhea. A quarter of the women reported stopping or decreasing the frequency of breast feeding during diarrhea. Reported cessation of breast feeding during diarrhea was associated with changing to special foods, and failure to note the onset of diarrhea or to recognize signs of dehydration. The withdrawal of breast feeding during episodes of illness and diarrhea is related to lack of knowledge regarding diarrhea. These data indicate that even in this population, with free access to preventive and curative medical care, there should be greater efforts to educate mothers to detect diarrheal disease and to maintain breast feeding during the diarrhea.