This paper reports on the outcome of nursing intervention consisting of information-giving to patients about to undergo a threatening medical event (intravenous pyelography) Thirty patients in an intervention group were given structured information on all aspects of the examination (sensory, procedural and temporal components, and a coping mechanism) Their reactions to the event as recorded in self-reports were compared with those of 30 patients who did not receive such information (control group) No differences were found between the groups regarding physiological reactions to the stressful event, but there were dear and partly significant differences in the psychological outcome variables Less pain and discomfort were experienced during intravenous pyelography in the intervention group and the subjects of this group were better able to form mental images of the impending event