Background: The regulation of banks is increasing in order to stabilize the financial market. Despite this increase in regulation, financial crises still continue to occur. The Basel Committee on Banking Supervision is gradually increasing the capital requirements for banks, yet the increase in capital requirements doesn?t seem to solve the problem. This raises the question: how does capital regulation affect banks? Purpose: The purpose of this study is, primarily to illustrate the effects that capital regulation has on risk and efficiency on banks within the European Union, but secondary also study the relationship between risk, efficiency and capital regulation.Method: To achieve the purpose of this study, a deductive approach has been used, where the problem is assumed to be due to an agency problem.