Glutaraldehyde appears to preferentially effect the activation processes of the adenylate cyclase complex of turkey erythrocyte membranes. The primary effect of low concentration (0.01 percent, 0.05 percent, and 0.1 percent) glutaraldehyde membrane treatment is to decrease catecholamine-stimulated cAMP formation. The effect can be blocked by prior activation of the system with isoproterenol + p[NH]ppG. 0.6 percent glutaraldehyde treatment of membranes has substantial effects on both F(-)- and catecholamine-stimulated cAMP production. The effects are blocked by prior activation of the adenylate cyclase complex with NaF, but not by isoproterenol + p[NH]ppG. Glutaraldehyde at these concentrations has no effect on Mn++-stimulated cAMP formation. The data is discussed with respect to the organization of the major macromolecular components of the adenylate cyclase complex as it exists within the native membrane prior to and following activation of the system.