Discussions about biotechnology tend to assume that it is something to do with genetics or manipulating biological processes in some way. However, the field of biometrics-the measurement of physical characteristics-is also biotechnology and is likely to affect the lives of more people more quickly than any other form. The possibility of social exclusion resulting from the use of biometrics data for such uses as identity cards has not yet been fully explored. Social exclusion is unethical, as it unfairly discriminates against individuals or classes of people. Social exclusion is unethical, as it unfairly discriminates against individuals or classes of people. This article looks at some of the ways in which social exclusion might arise from the use of biometric data, and introduces a model of balancing individual interests with which to analyse whether it is justified to run the risk of excluding some members of society for the benefit of others.