History and Objectives: Due to the prevalence of persistent diarrhea and its complications and the controversies regarding its etiology, the present study was performed in patients referred to Kashan’s Shaheed Beheshti hospital in 1989-94 to determine the relationship between malnutrition and persistent diarrhea.

Materials and Methods: In this case-control study, 100 children with persistent diarrhea were selected as the case group and 200 children with acute diarrhea were chosen as controls. And child with a sudden inset of diarrhea lasting more than two weeks and less than four weeks was considered a case of persistent diarrhea. The cases and controls were matched based in sex, time of referral to the hospital, onset of diarrhea and other factors influencing persistant diarrhea. Malnutrition was defined as a weight index of less than 90% of the normal weight. The role of malnutrition in persistent diarrhea was determined by calculating the relative risk and confidence interval.

Results: 10% of the children with acute diarrhea and 55% of those with persistent diarrhea had malnutrition (P<0.001). The risk of developing persistant diarrhea was 11 times greater in the presence of malnutrition. ]

Conclusion: Due to the remarkable role of malnutrition in the incidence of persistent diarrhea, we suggest more attention be paid to the problem of malnutrition in children and further studies be performed to identify its causes.