Distribution of technetium-99m stannous pyrophosphate was studied in mice with experimentally induced viral myopericarditis. Myocardial and bone uptakes of Tc-PPi were compared in 55 mice inoculated with coxsackievirus B3 (Nancy strain). The myocardium-to-bone uptake ratio in 33 mice with myopericarditis was increased to a greater extent than that seen in 22 mice without myopericarditis (p less than 0.001). In the severely involved heart, the uptake per gram exceeded that in the bone. Myocardial uptake in myopericarditis can be visualized on a whole-body image using a pinhole collimator and a left lateral view. Our experimental studies suggest the potential clinical usefulness of myocardial scintigraphy in viral myopericarditis.