Urine was collected at 4-hr intervals over a 24-hr span in 87 boys and 106 girls 11 +/- 1.5 years of age and over one or several 24-hr spans in 62 elderly men and in 85 elderly women 77 +/- 8 years of age. Epinephrine, norepinephrine, and dopamine were determined by HPLC. The data were analyzed by cosinor and by one-, two-, and three-way ANOVA. Children and elderly subjects showed circadian rhythms of urine volume and of the excretion of norepinephrine, epinephrine, and dopamine. While the urine volume was higher in the elderly subjects than in the children, norepinephrine, epinephrine, and dopamine excretion in the girls and epinephrine in the boys showed a statistically significantly higher mesor than in the elderly subjects of the same sex. There was a sex difference, with lower values in all variables in the girls and women compared to their male counterparts; the circadian amplitudes of norepinephrine, epinephrine, and dopamine in the girls and of epinephrine in the boys were higher than the circadian amplitudes in the elderly subjects. The circadian timing in urinary excretion between the elderly subjects and the children was different, with a consistent phase delay; the acrophase of the circadian rhythm in the elderly subjects moved in the night hours. In contrast, there was no age difference in the acrophase of norepinephrine and epinephrine excretion or in dopamine in the females. In the males, the circadian rhythm in dopamine excretion in the elderly subjects did not quite reach statistical significance at the P less than 0.05 level. Circannual variations with high values in winter and low values in spring and summer were found in norepinephrine excretion in boys, girls, and elderly women, but not in elderly men. In neither age group was there a statistically significant seasonal variation in epinephrine. Only in girls was a statistically significant circannual rhythm in dopamine excretion found, with highest dopamine values in the fall and lowest values in winter and spring.