In recent decades biomarkers have become accepted tools in clinical practice [1]. Although there is no widely accepted definition of what constitutes a biomarker, for the context of this review we consider a biomarker to be a protein or other macromolecule that is associated with a biological process or regulatory mechanism. Hence measurement of this biomarker in blood, for example, might provide quantitative information that could be clinically helpful regarding this biological process or regulatory mechanism. In this paper we review recent advances with the use of biomarkers in three major clinical areas: diagnosis of myocardial infarction, diagnosis and management of heart failure, and diagnosis and management of inflammatory conditions in general and systemic infections in particular. Although these may look like unrelated medical challenges, recent clinical research in these areas by our groups and others has opened up opportunities and challenges that seem fundamental for biomarkers in general.