This paper summarizes a ground-motion database developed for the NGA-Sub Project. The database consists of two- and three-component ground-motion recordings from selected earthquakes in subduction zones. The database also includes the supporting data such as source, path, and site metadata. The earthquakes are located in Japan, Taiwan, the Pacific Northwest region of North America, Alaska, Mexico, Central and South America, and New Zealand. The events in the database are classified as interface, intraslab, or outer-rise, and have magnitudes ranging from 4 to 9. The database includes more than 71,000 three-component recordings, most of which are from digital accelerograms. The database includes PGA, PGV, pseudo-spectral acceleration for eleven damping values between 0.5% and 30%, Fourier amplitude spectra for frequencies from 0.1 to 100 Hz, and significant-shaking durations based on Arias Intensity. These data are analyzed in the project to model various ground-motion properties.