Paired adrenals from feral male Mus musculus trapped from fields adjacent to the Memphis (TN) International Airport and from suitable control areas were incubated in the presence or absence of ACTH. Incubation media were assayed fluorometrically for corticosterone. Control animals exhibited lower basal secretion rates of corticosterone when compared to their noise exposed counterparts. However, ACTH elicited a significantly greater increase in corticosterone secretion in controls as compared to the noise exposed group. The data suggest a noise related decline in adrenal cortical responsiveness to ACTH.