Human papillomavirus type 16 (HPV-16) has been established beyond doubt as a causative agent in oropharyngeal squamous cell carcinoma (SCC). The incidence of oropharyngeal cancer has risen in recent decades, as has the proportion of patients who have a biologically relevant HPV-16 infection. Combined data from 14 recently published studies (2006-2010) show that 57% of 1316 reported cases of oropharyngeal SCC were HPV-16 positive. They had significantly better prognosis (hazard ratio (HR) for 5-year overall survival range 0.05-0.64), although smoking and higher T stage often appear as confounding factors to this favourable prognostic benefit. HPV-16 therefore has increasing importance as a clinically useful prognostic biomarker, but a benefit in survival has been seen in the use of surgery, radiotherapy, and chemotherapy, so specific changes in the preferred methods of treatment are hard to justify. Future trials that include oropharyngeal SCC will consider HPV-16 routinely as a stratification factor, and its use as a predictive biomarker awaits the development of effective targeted treatments. The undeniable and impressive prognostic significance of HPV-16 should hasten its addition to standard pathological reporting of oropharyngeal SCC, and ultimately to its inclusion in TNM staging systems of the American Joint Committee on Cancer (AJCC) and the International Union against Cancer (UICC).