Background: Preoperative anxiety is a frequent event that depends on multiple factors. One is the prior information to the patient, which must be simple, understandable and reliable. The aim of this study is to establish the relationship between the degree of information of the surgical procedure and the level of preoperative anxiety in patients scheduled for surgery. Material and methods: Cross-sectional study of 99 randomly selected patients scheduled for surgery at the Hospital Royo Villanova (sector I at Zaragoza). APAIS and STAI-AE scales were used to assess the preoperative anxiety level and the degree of prior information. The statistical analysis was performed using SPSS v.21.0, with the Chi-square test, ANOVA test and the nonparametric Kruskal Wallis to study the association between the different questions and the degree of anxiety. To assess the association of the two scales Pearson correlation test was used. Results: The educational level, type of surgery, previous surgery, specialty and previous surgery variables do not show statistical significance (p <0.05) compared to the anxiety level variable. It has been shown that there is an association between the degree of information and level of anxiety. Conclusions: The data shown in the present study support the hypothesis that patients who believe they need more knowledge about the surgical procedure have higher anxiety levels than patients who believe they need less.