The indication for an initial cranial computed tomography (CCT) in minor head trauma (MHT) patients remains the subject of discussion. The aim of this study was to investigate whether a newly developed, rapid test system (ELECSYS S100, Roche Diagnostics) might allow a diagnostically valid, reproducible measurement of S 100 in MHT patients. Blood samples were drawn from 75 MHT patients, a CCT scan was performed, and those with a post-traumatic intracranial lesion counted as CCT+. Results were compared to a healthy control group (n=17). Of the 75 patients included in the study, 14 were stratified as CCT+. The systemic concentration of S 100 in these CCT+ patients was significantly increased (0.31 microg/l) compared to the healthy control group (0.04 microg/l) as well as to the CCT-negative patients (0.08 microg/l). The ELECSYS S100 system allows a rapid, valid, and reproducible assessment of S 100B in patient serum and this concentration is significantly elevated in patients suffering from intracranial lesions as shown by initial CCT scan. Hence, this study is the basis for a multicenter trial currently underway to confirm the results of our pilot study.