Objectives: The aim of the study was to assess the effect of probiotics ondiarrhea during in- and outpatient treatment of children with severe acutemalnutrition (SAM).Methods: A randomized, double-blind, placebo-controlled study wasconducted involving 400 children admitted with SAM. Patients received 1daily dose of a blend of Bifidobacterium animalis subsp lactis andLactobacillus rhamnosus (10 billion colony-forming units, 50:50) orplacebo during hospitalization followed by an 8- to 12-week outpatienttreatment period, depending on patientsâ recovery rate. All outcomes werereported for in- and outpatient treatment separately. The primary outcome wasnumber of days with diarrhea during hospitalization. Secondary outcomesincluded other diarrhea outcomes, pneumonia, weight gain, and recovery.Results: There was no difference in number of days with diarrhea betweenthe probiotic (n ¼ 200) and placebo (n ¼ 200) groups during inpatienttreatment (adjusted difference þ0.2 days, 95% confidence interval 0.8to 1.2, P ¼ 0.69); however, during outpatient treatment, probiotics reduceddays with diarrhea (adjusted difference 2.2 days 95% confidence interval3.5 to 0.3, P ¼ 0.025). There were no effects of probiotics on diarrheaincidence and severity or pneumonia, weight gain or recovery during in- oroutpatient treatment. Twenty-six patients died in the probiotic versus 20 inthe placebo group (P ¼ 0.38).Conclusions: Bifidobacterium animalis subsp lactis and Lactobacillusrhamnosus had no effect on diarrhea in children with SAM duringhospitalization, but reduced the number of days with diarrhea inoutpatient treatment by 26%. Probiotics may have a role in follow-up ofhospitalized children with SAM or in community-based treatmentof malnourished children, but further studies are needed to confirm this.Key Words: diarrhea, low-income country, probiotic, severe acutemalnutrition, young children