In this doctoral thesis, we focus on biostatistics, risks and risk analysis in thefield of medicine, a science which has been using methods from the area of riskanalysis for a long time. The seven papers (paper I - paper VII) presented in this thesis, together with a general introduction to risk, risk analysis and decision-making, will be used to illustrate and discuss risk analysis as a tool for decision-making in the field of medicine. From my point a view, risk analysis in the field of medicine aims to reduce pain, raise the quality of life, reduce the risk of adverse events, compare cost efficiency between different treatment regimes and prolong a healthy life. Based on results presented in the thesis, we conclude that biostatistics, risks and risk analysis used in the field of medicine are valuable methods for evaluation of hypotheses within the health care area and a good basis for decision-making.