Twenty-four male Guatemalan children, aged 7 to 23 mo, suffering dehydration due to acute diarrhea were studied to assess their fecal endogenous losses of trace minerals zinc, iron, and copper while treated with oral rehydration therapy, either with standard or glycineadded solutions. Sodium and potassium excretions (from endogenous and exogenous sources) were also monitored. No statistically significant effect of glycine was observed on any of the minerals studied, although a tendency to higher output was seen with zinc. Median rates of fecal excretion of zinc, iron, and copper were 6.08, 6.33, and 1.61 µg/ kg/ h, respectively, whereas those for sodium and potassium were 11.2 and 9.7 mg/ kg/ h. All of the minerals' excretion showed significant linear correlations with fecal volume, r values were 0.47 (Zn), 0.64 (Fe), 0.77 (Cu), 0.98 (Na), and 0.97 (K). Mineral-mineral interactions also were evident, with such correlations in fecal excretion rates as: Zn versus Cu,r=0.75; Zn versus Fe,r=0.62; Fe versus Cu,r=0.76.