Analyses for trace elements were made on diets and excreta of two subjects on ad libitum diets for 30 days. The intake of each element was essentially the same for the two individuals. For the essential elements calcium, iron, magnesium and phosphorus the subjects were in balance and the patterns of excretion were the same. For minor trace elements, essential and non-essential, the excretory patterns differed widely. Estimates of f1 for strontium based on fecal and urinary excretion gave values of 0.50 and 0.39; estimates based on urinary excretion gave values of 0.26 and 0.51.