Patients with metastatic or locally advanced gastrointestinal stromal tumors (GIST) who develop resistance against the two hitherto approved drugs for this disease, the tyrosin kinase inhibitors (TKIs) imatinib and sunitinib, have a poor prognosis. Sometimes a further response may be achieved by other drugs, mainly other TKIs, which have been explored in different studies but not yet have been approved for clinical use. Pazopanib is a TKI inhibiting the tyrosin kinases KIT, PDGFRA, and VEGF 1-3, all of which have important roles in the pathogenesis of GIST. Theoretically, it may function in GIST, and it deserves investigational trials. The drug is approved for metastatic renal cancer and is relatively well tolerated. In this trial (SSG XXI), the disease control rate (DCR) = (CR+PR+SD) after 12 weeks of treatment will be assessed as the primary endpoint, and at the same time trough levels will be measured. Secondary endpoints include ORR, PFS, toxicity, and disease control rate in relation to trough level week 12 and in relation to the primary mutation of the tumor (if known). The goal is to include 72 patients in the trial, which is open and single arm.