Sunitinib malate (SU011248, Sutent®[Pfizer]) is an oral multitargeted tyrosine kinase inhibitor with efficacy against renal cell carcinoma (RCC) and gastrointestinal stromal tumor (GIST). Sunitinib has been approved by various regulatory authorities for treatment of advanced RCC and unresectable and/or malignant GIST following failure of imatinib mesylate treatment due to resistance or intolerance. Sunitinib is generally well tolerated, with most side-effects being mild to moderate. The most common adverse events are lethargy, diarrhea, stomatitis, hand–foot syndrome and hypertension. Uncommon but important adverse effects are hypothyroidism and hematological toxicity (neutropenia and thrombocytopenia), which require monitoring. Caution is recommended when using concurrent inhibitors or inducers of CYP3A4. The frequency and severity of side-effects often correlates with increased drug exposure. In clinical trials, side-effects seldom led to treatment discontinuation. This paper summarizes the published literature and provides recommendations for patient assessments and management of treatment-related side-effects.