The cutaneous sweat loss of calcium, copper, iron, magnesium, manganese, potassium, sodium and zinc of preadolescent boys on diets containing 30, 60, and 90 g protein and various mineral concentrations were studied. Arm sweat collections were made using the arm bag technique. Mineral and nitrogen concentrations were determined by atomic absorption spectrophotometry and the micro-Kjeldhl procedure, respectively. Total body mineral loss was extrapolated from arm sweat mineral and nitrogen loss and total body nitrogen loss. The influence of protein and mineral intake on mineral excretion in sweat was also studied. Statistical analysis (α= 0.05) showed no effect of protein and mineral intake on cutaneous mineral excretion. Arm sweat results are in accordance with those found by other researchers working with children but total body mineral losses are much lower than those found in research done with adults. / M.S.