FSH and LH excretion were correlated with melatonin excretion in consecutive daily urines obtained from a normal adult female (27 days), a normal 11-year-old girl (28 days), and an 8-year-old girl with idiopathic sexual precocity (30 days). Additionally pregnanediol-3-glucuronide (PG) excretion was determined in the urines of the adult female. Gonadotropin and PG excretion patterns of the adult female were those associated with a normal menstrual cycle. Excretion of melatonin, mean +/- SD, (11.3 +/- 2.7 vs 4.7 +/- 1.4 ng/h, p less than 0.005) was greater and PG (38.3 +/- 81 vs 124.2 +/- 46.7 ug/h, p less than 0.005) was less during the first 13 days as compared to the subsequent 14 days. Gonadotropin and melatonin excretions correlated positively (first 13 days FSH, r = 0.828; rs = 0.815 and LH, r = 0.816; rs = 0.905, p less than 0.005 and subsequent 14 days FSH, r = 0.607; rs = 0.685, p less than 0.025 and LH, r = 0.490, p less than 0.05; rs = 0.638, p less than 0.025). Excretion of PG and melatonin did not correlate during the first 13 days. However, during the subsequent 14 days they correlated negatively (r = -0.679, p less than 0.005; rs = -0.620, p less than 0.025). During the 28-day period the gonadotropin and melatonin excretion patterns of the 11-year-old girl showed random fluctuations and correlated positively (FSH, r = 0.669; rs = 0.631 and LH, r = 0.690; rs = 0.695, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)