Diastolic heart failure is increasing in prevalence. Although the pathophysiology is incompletely understood and current therapeutic strategies are limited, identification of diastolic dysfunction is important. We review the role of contemporary techniques with echocardiography and cardiac magnetic resonance imaging (CMRI) in the assessment of diastolic dysfunction. Cardiac catheterization is the criterion standard for demonstrating impaired relaxation and filling by making direct measurements; however, echocardiography has replaced it as the most clinically used tool. By evaluating mitral inflow pulsed-wave Doppler with and without the Valsalva maneuver, isovolumetric relaxation time, pulmonary venous flow Doppler, color M-mode velocity propagation, tissue Doppler imaging, and speckle tracking, echocardiography is considered an accurate method for diagnosis and grading diastolic dysfunction. Evaluation of diastolic function can also be performed by CMRI. Mitral valve inflow velocities, early deceleration time, and pulmonary vein flow velocities are diastolic parameters that can be measured by phase-contrast CMRI. Cardiac magnetic resonance imaging steady-state gradient echo can evaluate functional dimensions for time-volume curves; and myocardial tagging can assess ventricular diastolic “untwisting,” which may be important for improved pathophysiologic understanding. Studies have compared echocardiography and CMRI for diagnosing diastolic dysfunction in small patient groups with similar results. Cardiac magnetic resonance imaging can now provide clinically relevant data regarding the underlying cause of diastolic dysfunction and offers promise to gain mechanistic insights for therapeutic strategy development and clinical trial planning.