To determine whether accelerated intravenous (i.v.) rehydration using a new Isotonic Dehydration Worksheet results in: (1) complications in serum sodium or volume status, and (2) decreased duration of i.v. fluid therapy or length of hospital stay, we conducted a retrospective cohort study utilizing chart review. An intervention group of 98 children, ages 1 month to 12 years, treated with the Isotonic Dehydration Worksheet from December 2000 through March 2001 was compared to a control group of 61 children treated from December 1999 through March 2000 before introduction of the Worksheet. Complication rates were low and did not differ between the 2 groups. Mean unadjusted lengths of i.v. therapy (35.3 vs. 33.7 hours) and of hospital stay (47.0 vs. 49.3 hours) were not significantly different between the 2 groups. Introduction of an accelerated rehydration protocol was well-tolerated by patients but did not result in a significant decrease in the outcome variables examined. Other factors may have a greater impact on the outcome variables, and a prospective study to address these questions is planned.