Boron nitride nanotubes (BNNTs) represent an innovative and extremely intriguing class of nanomaterials, and preliminar but encouraging studies about their applications in biomedicine have emerged in the latest years. As a consequence, a systematic investigation of their biosafety has become of fundamental importance in the biomedical research. Extending our previous pilot in vivo study, here we present biocompatibility data of BNNTs injected in rabbits at a dose up to 10mg/kg. No significant adverse effect was found up to 7 days since their administration, and no impairments in blood, liver and kidney functionality were highlighted. Moreover, a terminal half-life circulation of about 90min was found. All the collected data are very promising, suggesting the optimal biocompatibility of BNNTs, and thus enabling their exploitation in nanomedicine as nanotransducers and nanocarriers.