Urinary free cortisol responses to five cage sizes, cage level, room change, tethering adaptation, chronic catheterization, and ketamine sedation were measured in 14 female and 14 male wild-born adult Macaca fascicularis. Urinary free cortisol, a physiological measure of psychological well-being that can be collected unobtrusively, provided a measure of the animals' general adrenocortical response to various conditions over a time course of hours. Urinary free cortisol values in response to stimulation with adrenocorticotropic hormone (ACTH) validated the measure as a reflection of blood values. Cortisol values were expressed as a ratio to creatinine, which normalized for differences in urinary output and body weight (muscle mass). Cage size (20–140% of regulation floor area) and housing level (upper vs. lower cage) had no effect on stress, as measured by cortisol excretion. Room change elicited a slight increase in cortisol excretion for the first day, but not to a level suggesting stress. Sedation, surgery, some aspects of tethering adaptation, and chronic catheterization produced urinary cortisol evidence of stress. Even so, animals varied in their responses and all showed adaptation. Males and females did not differ in normal mean values but females tended to have higher cortisol levels in response to potential stressors investigated in this study. Cortisol levels continued to decline gradually throughout the study. © 1993 Wiley-Liss, Inc.