Objective: To assess biochemical characteristics of adrenarche in patients with myelomeningocele (MMC), we examined serum levels of dehydroepiandrosterone sulfate (DHEAS) in prepubertal MMC patients. Patients and Methods: The study included a total of 54 prepubertal patients with MMC and shunted hydrocephalus: 13 patients (2 m, 11 f; aged 4.6–10.1 years, mean 8.1 ± 0.4) with isolated pubarche (Tanner stage PH 2–4, B1 or testes volume ≤3 ml) and 41 prepubertal MMC patients without pubarche (17 m, 24 f; aged 2.0–11.9 years; mean 6.8 ± 2.5). DHEAS levels were measured directly by chemiluminescence immunoassay (Nichols, USA). Auxological data (supine length, body mass index (BMI), arm span) and bone age (BA) were recorded. Results (mean ± SD): Basal DHEAS levels correlated with chronological age (CA) (r = 0.32, p < 0.05), BA (r = 0.65, p < 0.01; n = 23), BMI (r = 0.54, p < 0.01) and pubic hair stage (PH1 vs. PH2–4, r = 0.49, p < 0.01). 10/11 patients aged 2–4 years had DHEAS levels in the normal range, whereas 18/40 (45.0%) of the 5- to 9-year-old patients showed elevated levels (>+2 SDS). Ten patients with isolated pubarche (10/13; 2 m, 8 f; CA 8.3 ± 1.5 years) and 9 patients without pubarche (9/41; 6 m, 3 f; CA 6.9 ± 2.1 years) had elevated DHEAS levels (+6.34 and +4.05 SDS, respectively). The values correlated with BA/CA ratio (p < 0.05, n = 23). There was a trend to higher BMI SDS levels in patients with elevated DHEAS levels. Conclusion: Our data show an early and increased activation of adrenal androgen secretion in MMC patients.