We present an overview of reproducible 3D seismic data processing and imaging using the Madagascar open-source software package. So far, there has been a limited number of studies on the processing of real 3D data sets using open-source software packages. Madagascar with its wide range of individual programs and tools available provides the capability to fully process 3D seismic data sets. The goal is to provide a streamlined illustration of the approach for the implementation of 3D seismic data processing and imaging using the Madagascar open-source software package. A brief introduction is first given to the Madagascar open-source software package and the publicly available 3D Teapot Dome seismic data set. Several processing steps are applied to the data set, including amplitude gaining, ground roll attenuation, muting, deconvolution, static corrections, spike-like random noise elimination, normal moveout (NMO) velocity analysis, NMO correction, stacking, and band-pass filtering. A 3D velocity model in depth is created using Dix conversion and time-to-depth scaling. Three-dimensional poststack depth migration is then performed followed by - deconvolution and structure-enhancing filtering of the migrated image to suppress random noise and enhance the useful signal. We show that Madagascar, as a powerful open-source environment, can be used to construct a basic workflow to process and image 3D seismic data in a reproducible manner.