Background: This study was designed to examine the effects of preparatory cognitive and behavioral information on self-confidence, anxiety, and negative affect elicited by an impending upper gastrointestinal endoscopy. Methods: Forty-eight male and female out-patients, between 18 and 65 years of age, scheduled for a first-time, non-emergency, endoscopic examination were randomly assigned to receive one of four experimental interventions: cognitive, behavioral, combination, or attention-control. Measures of self-reported anxiety and self-reported self-confidence were obtained. Results: Cognitive and combination intervention subjects were statistically younger than behavioral and attention-control subjects. A credibility assessment revealed that subjects who were taught visualization used it during their procedure. Results indicated that subjects in the cognitive and combination interventions experienced significant reduction in anxiety and increase in self-confidence from pre- to post-intervention. Self-confidence did not increase for subjects receiving the behavioral-only or the attention-control interventions. Conclusion: The results of this study show that preparatory information in general is effective in reducing anxiety and in increasing self-confidence before an upper gastrointestinal endoscopy. Results suggest that teaching subjects visualization before a procedure increases their use of visualization during a procedure. (Gastrointest Endosc 1998;48:341-7.)