There are a number of factors about the UK military which could put them at a greater risk of physical health problems and mortality than the general population. There are very high levels of alcohol use and drinking is an accepted part of military culture. In addition, military personnel are more likely to experience stressful events than the general population, particularly during deployment. Many of these stressful events have previously been found to be associated with mental health problems. The King's Centre for Military Health Research (KCMHR) cohort study was set up to look at a representative sample of UK military personnel, and collected data on mental health, alcohol use and deployment experiences. The study found that 13% of the military are abusing alcohol at a level which is hazardous to their health and overall, levels of alcohol use are much higher than the general population at all ages. Research findings from the general population have shown that both alcohol use and mental health problems are associated with poorer physical health outcomes. Therefore, it is predicted that current and future healthcare use for physical conditions will be high in the UK military population. Identifying the future healthcare needs of military personnel and veterans is a current priority for the UK government. However, the current datasets that are available to look at use of healthcare services (and the reasons why) do not identify whether or not an individual is in the military. The proposed study will be able to identify military personnel in existing NHS datasets for England, Wales and Scotland that include secondary healthcare records, by linking to the KCMHR cohort data. In NHS hospitals, data is recorded each time someone is admitted to hospital as an inpatient, or has an outpatient visit or visits an accident and emergency department. The reason for the hospital visit is coded using an existing international classification of disease and health related problems (ICD-10). This data is collated from all hospitals and is called Hospital Episode Statistics (HES) in England. In this study, English, Scottish and Welsh data will be linked with the KCMHR cohort study, providing information on approximately 10,000 military personnel. This will offer a unique opportunity to study the health of UK military personnel and will provide data on the health problems for which they most commonly seek help. We will be able to identify whether physical health conditions or accidents and injuries are most common. A further aim for the study will be to look at whether we can predict if an individual is likely to be admitted to, or visit hospital, for a physical health condition or an accident or injury, by using the information from the KCMHR cohort about how much alcohol they drink and whether they have a mental health problem. We will also be able to look at the costs to the NHS resulting from high levels of alcohol use and mental health problems within the military. It is a high social, health and political priority to identify the future health care needs of the UK military (serving and ex serving), so that the NHS commissioning board have the data they need in order to plan specialised commissioning of health care services. It is also very important to find out more information about the links between alcohol use, mental health problems and physical ill-health in military personnel. This is so we can identify which military personnel are most at risk of having poorer physical health in the future and also so that there is evidence that existing policies regarding the use of alcohol within military settings may need to be changed.