A cross-sectional sampling survey of mothers' practice of ORT in Amphoe Bunpotphesai in the northern part of Thailand included 1,619 children under five. Two hundred and six children were reported to have 223 diarrheal episodes. The incidence of diarrhea in children under five was 3.4 episodes per child per year. When children had diarrhea 65.5 per cent of mothers sought help from health providers, 25.2 per cent treated their children with drugs bought from stores, 2.3 per cent used herbal medicine and 6.1 per cent did not treat their children. 50.7 per cent of diarrheal episodes mother gave ORT, using ORS 19.7, commercial electrolytes mixture 16.6 and home available fluid 14.4 per cent. The accuracy of dilution of electrolytes powder from the packets was checked in 80 incidences. 31.8 and 27.8 per cent of mothers made correct dilution of ORS and commercial electrolytes products respectively. Health providers carried both ORS and commercial electrolytes packets. ORS added to a glass of water was found in 13.6 per cent which was 3 times concentrated. Commercial electrolytes products were too dilute in 72.2 per cent. 17.5 per cent of mothers divided electrolytes powder to add in one spoon of water to treat their children as one drug dose. Data showed that the ORT use rate was 50.7 per cent. Home available fluid was used by 14.4 per cent. ORT should be further promoted to control diarrheal diseases and health providers should give instructions to every mother or child minder on how to dispense ORS or electrolytes packets for appropriate dilution and use.