The present study attempted to: (1) simplify the existing enzyme immunoassay (EIA) for the measurement of insulin-like peptide 3 (INSL3) concentrations in goats (2) to measure circulating INSL3 and testosterone in pre-pubertal Jamnapari X local crossbred goats (3) to examine the relationships among INSL3 concentration, testosterone concentration, scrotal circumference and body weight during the pre-pubertal age. Serial blood samples were collected from normal pre-pubertal male Jamnapari X local crossbred goats (n = 6) at the ages of 19 to 28 weeks. Serum INSL3 was measured using a recently reported EIA with modifications to the original procedure. The detection ranges of the INSL3 and testosterone assays were 0.08 to 80 ng/mL and 0.01 to 40 ng/mL, respectively. The intra-assay coefficient of variations were 3.79% for INSL3 (n = 6) and 3.72% (n = 6) for testosterone. Serum INSL3 concentrations ranged from 13.62 ± 3.25 to 22.45 ± 6.09 ng/mL (mean ± SEM) in pre-pubertal goats. Those concentrations increased (p < 0.05) from 20 (13.62 ± 3.25 ng/mL) to 22 (22.45 ± 6.09 ng/mL) weeks of age. Testosterone concentrations ranged from 0.30 ± 0.07 to 1.22 ± 0.43 ng/mL in pre-pubertal goats. A significant drop was observed in testosterone concentrations at 23 weeks of age. INSL3 was correlated (r = 0.58; p < 0.05) with scrotal circumference while no significant correlation was observed among other tested parameters. A rapid, sensitive EIA system was simplified to quantify INSL3 in goats, by simplifying the existing procedure. Different serum INSL3 and testosterone dynamics were found from 19 to 28 weeks of age of the goats. Compared with testosterone, INSL3 dynamics seemed to be more consistent with the age of pre-pubertal goats and showed a relationship with the testicular growth.