Microwave (MW) ablation therapy is a local treatment by which tumours are destroyed by coagulation from the passage of MWs into cells. The aim of this review is to examine histological results obtained from preclinical and clinical studies. A literature search was undertaken for all studies focusing on MW therapy and in which lesions were excised for a complete histopathological examination after treatment. Two main zones were described after ablative therapy (central and transitional). Both corresponded to specific microscopic characteristics and evolved over time in a precise manner. No viable cells even up to 6 cm in diameter were demonstrated in 93% of lesions after treatment. Microwave therapy is a reliable technique under a variety of clinical situations. Future investigations are needed to compare MW with other ablative techniques to identify factors that influence the effectiveness of the various techniques and to determine specific indications.