Multiwalled carbon nanotubes (MWCNTs) are considered to be the ideal reinforcements for biorelated applications on account of their remarkable structural, mechanical and thermal properties. However, before MWCNTs can be incorporated into new and existing biomedical devices, their toxicity and biocompatibility need to be investigated thoroughly. In this study, regenerated silk fibroin/MWCNT nanocomposite films were prepared using a solvent system with pre-dispersed MWCNTs. Their biocompatibility was examined in vitro using human bone marrow stem cells. Scanning electron microscopy and a WST-1 assay demonstrated that the silk fibroin/MWCN film supported BMSC attachment and growth over 7 days in culture similar to the silk fibroin only film.