<p>Graphene has attracted much attention since its discovery and has been studied in variety of research fields from quantum physics to biomedical engineering due to its unique properties. The authors have focused on graphene&rsquo;s keen electrical response to charged biomolecules and investigated biosensing application of graphene field-effect transistor,naming it &ldquo;lab on a graphene&rdquo;. In this article, their research progress is reported. The charged biomolecules induce hole or electron carriers to graphene channel and can be detected as a drain current change. Graphene&rsquo;s high carrier mobility, two-dimensional structure and electrochemical stability achieve highly sensitive and speedy detection. While the bare graphene successfully detected pH changes, aptamer-modified graphene transistor realized specific detection of immunoglobulin E with the detection limit of 290 pM. The authors recently applied this high sensitivity to the detection of human-infectious avian influenza virus. In the preliminary results using pseudo-virus (lectin), glycan-modified graphene transistor shows high specificity of infectivity and sensitivity at subnanomolar range. Novel fabrication process for flexible graphene device and wireless operation of graphene transistor are also reported.</p>