Rational and Background: Diarrhea remains an important cause of morbidity and mortality among children under five (U5) in Laos. Complications of paediatric diarrhea are not uncommonly found among the children admitted to hospitals. Incorrect home¬care practice of children with diarrhea by their guardians may be an important factor contributing to such complications. Methodology: A cross¬sectional, descriptive study was carried out at three central hospitals of Vientiane Capital (Mahosot, Mother and Child, and Setthathirat) between January and February 2010 with objectives to (1) determine the frequency of diarrhea complications among U5 children, (2) describe home care behavior of diarrhea by care¬givers, and (3) correlate such behavior with complications. Results: During the study period 3,722 U5¬children presented or were admitted to the three hospitals. Of these 880 (24%) had diarrhea. Of all children with diarrhea, 262 children and their guardians were studied. All children had been treated before presenting to the study hospitals [home¬care by guardians (52%), treated in public hospitals (34%) and in private clinic (14%)]. One hundred and seventy¬one children (65%) had at least one complication at presentation including dehydration (48.5%), malnutrition (27%) and abdominal distension (12%) with one intussusception (0.4%). Treatments given to the children before presenting to the hospitals were ORS (83%), antibiotics (46%), anti¬diarrheals (25%), herbal medicines (8.5%), and antiemetics (5%). Ninety percent of the guardians had correct knowledge of diarrhea definition and on how to prepare ORS but only 32% and 27% of the guardians increased quantity of daily fluid and food, respectively, to their children during diarrhea. The mean (95%CI) years of schooling of the guardians whose children had complications at presentation were significantly lower than those whose children did not have complications [8.5 (8.1 – 8.9) vs 9.2 (8.2 – 9.6), P = 0.04]. Children who received anti¬diarrheals and antibiotics before presentation were 5 and 3 times, respectively, likely to have complications when compared to those who did not [OR = 4.9, 95%CI = 2.2¬10.9; P < 0.001 and OR = 3.4, 95%CI = 1.9 – 5.9; P < 0.001; respectively]. Children treated with anti-diarrheals and antibiotics prior to presentation were 26 and 5 times, respectively likely to have abdominal distension compared to those without treatment [OR = 26.1, 95%CI = 9.4-72.4; P < 0.001 and OR = 4.8, 95%CI = 2.0¬11.7; P < 0.001; respectively]. Children who were given normal quantity of fluid by the guardians during diarrhea were 1.5 times likely to be dehydrated when compared to those who received increased quantity of fluids [OR = 1.6, 95%CI = 1.1¬2.2; P = 0.002]. Conclusion: Half of Lao U5¬children with diarrhea admitted or presented at central hospitals in Vientiane Capital had been treated by their caregivers and 2/3 of them had at least one complication. These complications were significantly associated with incorrect home¬care practice by the guardians especially treatments with anti¬diarrheals and antibiotics.