In this work, the Thermoelastic Stress Analysis (TSA) technique is used for the monitoring of fatigue crack growth during fracture mechanics tests on four stainless steels: AISI 422 and ASTM A182 grade F6NM with martensitic lattice and CF3M and CF8M with austenitic lattice. In particular, an automatic procedure based on the TSA technique was proposed for the continuous evaluation of the crack tip position and the SIF value. Advantages with respect to classical methods can be obtained in terms of reduction of: testing time, experimental set-up, data processing and data report.