Perivalvular extension of infection is a not-infrequent and potentially fatal complication of bacterial endocarditis. Because the efficacy of various modalities in the diagnosis of such complications is not well established, a selective review of the published literature on this issue is worthwhile. The electrocardiogram is the easiest study to obtain. It is quite specific in identifying perivalvular extension of infection when conduction system disease is demonstrated but has a low degree of sensitivity overall. Transthoracic two-dimensional echocardiography, transesophageal echocardiography, and color-flow Doppler echocardiography are the most practical and useful techniques for diagnosis of perivalvular extension of infection. Magnetic resonance imaging also appears to be an effective tool in this setting; however, because of a paucity of clinical data, its precise utility has not yet been determined. Nuclear medicine studies and computed tomography play a minimal role. Cardiac catheterization is as useful as the echocardiographic techniques but is invasive, not as readily available, and significantly riskier in terms of complications. An approach to the diagnosis of perivalvular extension of infection is proposed on the basis of the literature review.