Semiconducting silicon nanowires (SiNWs) have shown great potential for the electrical detection of human disease biomarkers. The technique for label-free detection using SiNWs allows for fast, efficient and inexpensive detection of biomarkers, unlike current time-consuming methodologies such as fluorescence ELISA or western blot. We demonstrate a proof-of-principle protein detection using biotinylated SiNWs for the detection of ultralow concentrations of streptavidin with a maximum sensitivity of up to 10 fM. Real-time detection of human cardiac troponin T using antibody-functionalized SiNWs is also presented. The possibility of large scale integration paves the way towards the simultaneous detection of a large number of protein biomarkers within a single chip and is of importance to the development of diagnostic tools as well as point-of-care applications. © International Federation of Medical and Biological Engineering 2009.