A randomized, double-masked clinical trial was completed to compare the effects of four dietary regimens for the nutritional management of 116 Peruvian children between 3 and 24 months of age with acute diarrhea. Diets consisted of a modified whole milk formula (group M), a lactose-hydrolyzed milk formula (HM), wheat noodles and whole milk (N-M), or wheat noodles and lactose-hydrolyzed whole milk (N-HM), all offered in amounts up to 55 kcal/kg body weight/day for the first 2 days of treatment and up to 110 kcal/kg/day for 4 days thereafter. The clinical characteristics of the patients in each group were similar initially. Treatment failure rates in the two milk groups combined (M = 14.3%, HM = 20.0%) were greater than in the two noodle-milk groups combined (N-M = 3.4%, N-HM = 3.4%), p = 0.03. The average stool outputs by children in both M groups (range 40–66 g/kg body weight per day on all study days) were consistently greater than those by children in both N-M groups (range 29–50 g/kg/day). The differences by dietary group were statistically significant on days 3 and 4 (p < 0.04, analysis of variance). The estimated median durations of illness [and 95% confidence limits (CL)] in each milk group (M = 138 h, CL: 88–214; HM = 113 h, CL: 75–170) were significantly greater than in each noodle-milk group (N-M = 52 h, CL: 35–76; N-HM = 67 h, CL: 45–100), p < 0.001–0.071. In this group of patients, noodle-milk mixtures produced fewer treatment failures, lower fecal outputs, and shorter durations of diarrhea than did milk alone, regardless of the lactose contents of the respective milks or mixed diets. Small differences in intestinal absorption and changes in body weight by dietary group that were identified were of minor clinical importance during the short duration of study. Thus, the noodle-milk diets employed during this study were safer than the milk diets for the dietary management of children with acute diarrhea.