Introduction The nursing degree of the University of Genoa has redesigned its curriculum, by applying the Project-Based Learning methodology to plan the learning activities in the intellective domain of professional competence. Aim of the study Test the usefulness of the clinical reasoning methodology when students make use of problem solving in the clinical setting. Sample The sample was chosen among second year and third year students of the Bachelor's Nursing Degree Course at the University of Genoa in the academic year 2007/2008 (for a total of 497 students). Of these 164 students, a sample of 60 students were randomly selected by means of a table of causal numbers and were split into group A and group B; the two groups were compared on the basis of an analysis of the numerousness and the distribution in order to report their significance. Methods The contract of clinical learning as a tool to define a personalized course for the student was used to define the aims. The experimentation was conducted during apprenticeship, where sessions of clinical reasoning experiences were included. In order to obtain objective evaluation data that would allow to measure the performance variations between the two study groups, the Triple jump examination was used. Results In this study we compared the outcomes on the improvement of problem solving performance after including, in the clinical apprenticeship course, the clinical reasoning methodology organized into sessions. Given these results, we decided to check by using two non-parametric tests, if the two performance obtained was solely the consequence of the different learning process. We used the Kruskalwallis Test and Mann-Whitney's U Test, which showed that the two groups reflected the entire population of students taken into consideration, and that therefore the initial characteristics of the two groups were homogenous. [ABSTRACT FROM AUTHOR]