PIP: Intravenously administered rehydration therapy was compared with orally administered rehydration therapy for treating children with diarrhea in a clinical study of 3000 children admitted to the Medical College Hospital, Kottayam, India. Oral rehydration was more effective and safer than intravenously administered fluid therapy. The 3000 children were divided into 2 treatment groups. The 1st group consisted of 1800 patients admitted between January 1970 and August 1972. The 2nd group consisted of 1200 patients admitted after September 1972. In the 1st group 72.3% of the cases were mild, 22.1% were moderate, and 5.7% were severe. Respective proportions for the 2nd group were 78.0%, 17.3%, and 4.7%. In the 1st group fluid was administered intravenously to the patients whenever it was needed. None were treated with orally administered fluids. In the 2nd group all the patients received oral rehydration therapy. In addition 1.3% of the mild cases, 10% of the moderate cases, and most of the severe cases received intravenously administered fluids. Abdominal distension occurred in 7% of the patients in the 1st group and in none of the patients in the 2nd group. Treatment duration was shorter for the second group. Venesection was necessary for 61 of the moderately dehydrated patients and 50 of the severely dehydrated patients in the 1st group but only for 5 severely dehydrated patients in the 2nd group. In the 1st group 4.5% of the moderately dehydrated patients and 34% of the severely dehydrated patients died. In the 2nd group none of the moderately dehydrated patients and only 18% of the severely dehydrated patients died. The occurrence of thrombophlebitis and septicemia were markedly reduced for the 2nd group compared to the 1st group.