Laminar to turbulent flow transition is a complex phenomenon that is currently widely investigated in the field of fluid dynamics. In particular, the study of time irreversibility - intended as statistical asymmetry of signals under time reversal - of a transitional boundary layer can offer new perspectives in the analysis of turbulence and non-stationary processes. Therefore, the connection between the turbulent structure of the boundary layer and the irreversibility of the velocity signals is an important subject of research. This thesis proposes a quantitative and point-to-point analysis of the time irreversibility of a transitional boundary layer and makes use of numerical data from the John Hopkins Turbulence Database (JHTDB), which simulate an incompressible flow on a flat plane subject to a bypass transition induced by isotropic turbulence at the inlet.