Sunitinib is a novel, multi-targeted receptor tyrosine kinase inhibitor, which has demonstrated evidence of improved survival when compared to interferon (IFN)-alpha in patients with metastatic renal cell carcinoma (RCC). Recently published National Institute for Health and Clinical Excellence guidance recommends sunitinib as a first-line treatment option for patients with advanced and/or metastatic RCC. We assessed the efficacy and toxicity of sunitinib in an unselected group of patients with metastatic RCC, and compared outcomes in clinical practice with published clinical trial results. Between June 2006 and March 2008, 56 patients with metastatic RCC gave informed consent for commencement of sunitinib treatment at our institution. Median age was 61 years (range: 33-78); 68% had clear-cell histology; 86% had undergone prior nephrectomy; and 50% had progressed on IFN-alpha prior to commencement of sunitinib. Sunitinib was administered orally at a dose of 50 mg once daily, in 6-week cycles consisting of 4 weeks of treatment followed by a 2-week break. All patients were evaluable for toxicity, and 49 for response. The mean dose of sunitinib was 38.15 mg/cycle (range: 25-50); and 402 cycles of sunitinib were delivered. Partial response and stable disease were observed in 41 and 37% of patients, respectively. Median progression-free survival and overall survival were 12.2 and 18.2 months, respectively. The most common adverse events (all grades) were mucositis (79%) and fatigue (75%). Grade 3/4 neutropenia was observed in 13%, and treatment-related hypothyroidism in 20%, of patients. Dose-reduction was necessary in 75% of patients, and 32% needed hospital admission for treatment-related toxicities. The results from this study confirm the efficacy of sunitinib in the first- and second-line treatment of an unselected group of patients with metastatic RCC. Compared to published data, there was a higher incidence of treatment-related toxicities and a greater necessity for dose-reductions. Despite the increase in toxicity, these results are encouraging and imply that the clinical trial results seen with sunitinib can be translated into routine clinical practice.