This project is designed to collect the evidence that will be needed to support the introduction of the cancer-preventing vaccine HPV (Human Papillomavirus) into the national immunization program of Vietnam. HPV is the second vaccine that has been developed that can prevent cancer (the first being Hepatitis B vaccine which prevents liver cancer). HPV vaccine prevents HPV infection, which is responsible for almost all cases of cancer of the cervix in women. In Western countries cancer of the cervix is much less common than in developing countries, because the regular cervical screening (Pap smears) identifies and treats very early cases. HPV is very common in developing countries like Vietnam, and the cancers that it causes are usually detected late, leading to high mortality. HPV is also responsible for a variety of other cancers affecting both men and women, including penile cancer, anal cancer and throat cancer. The vaccine is used is most industrialized countries, and is given to girls, and in some countries to boys as well. It has been introduced into very few developing countries, because of its high price, and the lack of evidence about HPV infection and disease in those countries. Vietnam is a rapidly modernizing country, with a booming economy and a population that is becoming increasingly westernized. HPV is spread by unprotected sex, and rates of infection are very high among sex workers and men who have sex with men. This project will study the rate of HPV infection among young university students in north, south and central Vietnam to get a national perspective. We will also study two important high risk groups, sex workers and men who have sex with men in both the north and south. We will use the records of the cancer hospitals in Vietnam to estimate the proportion of the population who were affected by HPV associated cancer, and to understand better the ages affected and the outcome and treatment costs of cases. This will enable us to predict the effect of HPV vaccine introduction on the community and calculate the money that will be saved by the health system if those cancers are prevented. Finally we will develop, within Vietnam, the laboratory skills that are needed to study HPV disease, and especially to undertake a trial of HPV vaccines in Vietnam. The trial is not covered by this proposal, but we hope in future to do a trial that will help us to decide which is the simplest and therefore least expensive, way to introduce HPV vaccine into a developing country like Vietnam. The project will be undertaken jointly by five institutions. The three Vietnamese institutions (two in the north and one in the south) will be able to share their expertise in this area and also develop new skills with help from expert groups in London (London School of Hygiene and Tropical Medicine) and Australia (Murdoch Childrens Research Institute).