What is medical informatics, and why should practicing physicians care about it? Medical informatics is the study of the concepts and conceptual relationships within biomedical information and how they can be harnessed for practical applications. In the past decade, the field has exploded as health professionals recognize the importance of strategic information management and the inadequacies of traditional tools for information storage, retrieval, and analysis. At the same time that medical informatics has established a presence within many academic and industrial research facilities, its goals and methods have become less clear to practicing physicians. In this article, I outline 10 challenges in medical informatics that provide a framework for understanding developments in the field. These challenges have been divided into those relating to infrastructure, specific performance, and evaluation. The primary goals of medical informatics, as for any other branch of biomedical research, are to improve the overall health of patients by combining basic scientific and engineering insights with the useful application of these insights to important problems.