Simultaneous acquisition positron emission tomography-magnetic resonance imaging (PET-MRI) has the ability to combine anatomic information derived from cardiac MRI with quantitative capabilities of cardiac PET and MRI and the promise of molecular imaging by specific PET tracers. This combination of cardiac PET and MRI delivers a robust and comprehensive clinical examination. It has the potential to assess various cardiovascular conditions, including assessment of myocardial ischemia, infarction, and function, as well as specific characterization of inflammatory and infiltrative heart diseases such as cardiac sarcoid and amyloid. It also offers fascinating possibilities in imaging other cardiovascular-related disease states, such as tumor imaging and vascular imaging. In this review, we begin with a general overview of the potentials of PET-MRI in cardiovascular imaging, followed by a discussion of the technical challenges unique to cardiovascular PET-MRI. We then discuss PET-MRI in various cardiovascular disease imaging applications. Potential limitations of PET-MRI and future directions are also considered.