Professional risk and security in the health sector is becoming ever more important : the number of accidents in hospital environments during 2005 was 19,000 and nurses were the most frequently involved category. This study deals with clinical risk perception . A questionnaire was issued to 259 student and 100 professional nurses at the Modena and Reggio Emilia University Hospital., comprising 70 questions regarding 5 dimensions: general risk perception, personal risk perception, nursing skills, observed experience and direct experience. Results were evaluated using the ANOVA and t-tests and showed significant differences among the various groups (first, second and third-year students and professional nurses) in relation to each dimension. On the whole , the perception of risk was relatively low in comparison to its real level in the working environment. Therefore, specific training for a correct perception of health risks is required, not only for students but also for trained nurses, so that the culture of risk management becomes a routine issue.