In recent years multi-pinhole SPECT systems have gathered significant attention. These instruments produce images with better spatial resolution than SPECT devices equipped with traditional collimators when imaging objects close to the pinhole, this makes them a popular choice for preclinical small animal experiments and some special cases of human diagnostics (for example brain imaging). As the imaging process of pinholes differs fundamentally from that of traditional parallel collimators, image reconstruction for these devices poses its own special problems. As both the iterative reconstruction techniques typical for this modality and the imaging characteristics of pinholes incur long running times, my principal goal was to parallelize the task and implement it on a graphics card. In this report I first outline the theoretical basis of multi-pinhole imaging and image reconstruction, then I introduce the implemented algorithms and finally I demonstrate their operation on some examples.