Objective: To determine the causes of anxiety about surgery and to assess the impacts of informing about the surgical procedures on anxiety. Methods: Between 18 and 65 years old, 497 patients who were scheduled for elective surgery in the Urology Clinic were included in this study. At the preoperative period, patients were asked to complete the following forms twice, before and after informing about surgery: State-Trait Anxiety Inventory (STAI), Visual Analogue Scale (VAS), European Quality of Life-5 Dimensions (EQ-5D) and the form containing causes of anxiety. Mean scores of STAI and VAS were classified as low, moderate, and high. Results: The mean age of the patients was 56.54±0.58 and the mean STAI value was 39.16±0.42. Factors increasing the level of anxiety were female gender, unemployment and lack of surgical history (p<0.05). No statistically significant difference was found among STAI and VAS scores of the age, educational level, disease (benign - malign) and operation groups. The most frequent causes of anxiety were post-operative pain (38.3%), fear of organ loss (21.3%) and quality of life impairment (18.9%). However, the first reason for anxiety in the group with a high anxiety score was fear of death. After the patients had been informed, the STAI and VAS scores increased. The anxiety levels increased after informing especially the patients who were unemployed women, low educated and undergoing group A (major) operation (p<0.05). STAI was positively correlated with VAS but negatively correlated with EQ-5D (p<0.01). Conclusion: It is observed that the patients who will undergo urological surgery have a moderate anxiety level and the most common cause is postoperative pain. Informing patients in the preoperative period increases the anxiety level. Hence, their quality of life is adversely affected. To understand the effects of informing on anxiety more clearly, new studies, including an uninformed control group, should be conducted. [ABSTRACT FROM AUTHOR]