The lithogenic and inhibitory substances in the 24-h urine of 150 healthy females and 150 healthy males were recorded. These two groups were further subdivided into 6 different age-groups, with 25 in each group. The 24-h excretion in these various age-groups displayed considerable differences in some cases, particularly in the case of the pH value, and the Ca, Mg, citrate and phosphate excretion of the women, and the Ca, Mg, uric acid, Na and K excretion of the men. All the parameters measured with respect to the males displayed higher levels of excretion than those of the females.