The purpose of this study is to examine the development of burnout throughout the working career on a sample of professional nurses. The longitudinal study was conducted in 4 different times of nurses’ career: the last year of nursing school, 6 month after working insertion, 1 year later and 13 years later. The hypothesis is to find a decrease of burnout over time. The results don’t support totally the hypothesis. In fact, data show that there are 2 critical moments during nurses career: we found higher levels of burnout at the second time (working insertion) and at the last one (after more than 13 years of working activity), that is the time where burnout levels are higher. Keywords: burnout, nurses.