GISTs have a heterogeneous clinical history. Also tumours initially considered benign can develop a recurrence. There are two main prognostic factors: mitotic index and tumour size; considering these parameters it is possible to stratify primary tumours into three classes of risk (high, intermediate and low). An high mitotic index and/or tumor size ≥ 10 cm are negative prognostic factors for predicting disease recurrence. The clinical history of GISTs is insidious because metastases can growth 20 years later after the primitive tumour resection. Therefore, for GIST patients it is required a lifelong follow-up (or at least not shorter than 10 years) by a multidisciplinary physician team composed by medical oncologists, surgeons, pathologists, radiologists, internists and nuclear medicine physicians. Follow-up visits for the first two years are scheduled every three months in case of high/intermediate risk tumours and every six months in case of low risk lesions. It is also recommended a CT scan be performed periodically. In selected cases other exams such endoscopy (if gastric lesion) or MRI (allergies to contrast media) may be preformed. If disease recurrence is suspected a PET-CT exam is recommended.