Adrenocortical carcinoma (ACC) is a rare neoplasm that affects between 0.5 and 2 new cases per million per year in Western countries. The majority of ACCs, about 50–60%, are functioning at presentation. Hypersecretion of cortisol and/or androgen are the most frequent alterations at disease presentation. Non-functioning tumors can present with mass symptoms or be discovered incidentally. The most important prognostic factors in early ACC are disease stage, margin-free resection, age, proliferation marker Ki67, and glucocorticoid excess whereas, in metastatic patients, high tumor burden, grade, Ki67 index, and uncontrolled symptoms are the major factors associated with worse prognosis. Different multiparametric scores have been studied in order to differentiate ACC cases on a prognostic basis and, in particular, the mGRAS score has been developed. mGRAS components are: grading, resection status, age, tumor or hormone-related symptoms, and stage according to the European Network for the Study of Adrenal Tumors (ENSAT) staging system.