BACKGROUND:Gastrointestinal disorders are common complaints for which endoscopy and colonoscopy are the most important diagnostic procedures.Anxiety is an unpleasant,ambiguous feeling of apprehension and fear of unknown origin that occurs during stressful situations or injury.Lack of sufficient information and fear of pain can cause anxiety prior to a colonoscopy,reducing the number of patients willing to undergo the procedure and increasing colonoscopy time.The aim of this study was to evaluate the efficacy of psychological preparation on anxiety before colonoscopy in patients presenting to Golestan Hospital during the years 1994 and 1995.MATERIAL and METHODS:This study was a double-blind clinical trial of patients presenting to the colonoscopy unit in Golestan Hospital in 1994 and 1995.A total of 80 patients were divided into two groups:intervention and control.A primary assessment of anxiety was performed using Spielberger’s State-Trait Anxiety Inventory.Before the colonoscopy,the State-Trait Anxiety Inventory was completed by the patients again.The effectiveness of psychological preparation before colonoscopy and its effect on anxiety were evaluated using statistical software SPSS 20.RE SULTS:The mean age of participants was 46.33 ± 12.2 years in the intervention group and 44.8 ± 12.26 years in the control group.In this study,there were 41 males (51.3％) and 39 females (48.7％);15 patients (18.7％) were single and the rest married.In terms of demographic variables,there were no significant differences between the two groups (p ＞ 0.05).The average scores of state and trait anxiety in the intervention group showed a statistically significant difference before and after the intervention (p =0.000).CONCLUSION:Trait and state anxiety levels after psychological preparation showed a statistically significant reduction.This indicates the effectiveness of intervention programs to reduce anxiety before colonoscopy.