The spider monkey (SM) (Ateles geoffroyi) a New World primate species native to Mexican forests, has become endangered in the wild due to environmental perturbations. Little is known about adrenal function and its relationship to reproduction in this species. Our objectives were to assess serum glucocorticoid (GC), mineralocorticoid (MC) and testosterone concentrations in captive SM and evaluate adrenal and testicular responses to potentially stressful animal handling procedures. Seven adult males, housed in a single mixed gender group in an off-exhibit enclosure at the University Park were captured for anesthesia every 2 months over a 1-year period. Blood samples were collected from each male at three time points: (1) ∼5–10 min after ketamine injection in the outdoor enclosure; (2) ∼2 hr later following animal transport to the laboratory and immediately after tiletamine–zolazepam injection; and (3) ∼20–30 min following the second anesthetic injection. Serum samples were frozen and later analyzed for cortisol, corticosterone, aldosterone and testosterone via radioimmunoassay. Cortisol was the primary GC detected in SM serum with much higher mean concentrations than for corticosterone. Capture, restraint and anesthesia resulted in significant increases in both cortisol and corticosterone concentrations. Whereas aldosterone concentrations were unchanged by animal handling procedures, testosterone concentrations significantly declined under anesthesia over time. In summary, these results provide data for the main adrenocortical hormones in male SM and characterize their acute adrenal responses to potentially stressful handling and anesthesia procedures. Our findings also suggest an interaction between acute increases in corticosteroids and decreased concentrations of serum testosterone. Zoo Biol. 32:641–647, 2013. © 2013 Wiley Periodicals, Inc.