The number of reports on drug facilitated crimes is increasing these last years. Apart from ethanol and cannabis, benzodiazepines (BZD) and analogs are the most common drugs reported to be used probably due to their amnesic and sedative properties. We have developed a rapid and sensitive method using LC-MS/MS triple stage quadrupole (TSQ) for the determination of single exposure to bromazepam (Lexomil, 6 mg) and clonazepam (Rivotril, 2 mg) in urine and hair of healthy volunteers. Chromatography was carried out on a Uptisphere ODB 5 microm, 2.1 mm x 150 mm column (Interchim) with a gradient of acetonitrile and formate 2 mM buffer, pH 3. Urine was extracted with Toxitube A (Varian) and allowed the detection of bromazepam, 3-hydroxy-bromazepam, clonazepam and 7-Aminoclonazepam for more than 6 days. Head hair, collected 1 month after the exposure, was treated by incubation with Soerensen buffer pH 7.6, followed by liquid-liquid extraction with dichloromethane for common BZD. A specific pre-treatment for amino-BZD, with an incubation of 15 min at 95 degrees C in 0.1 N NaOH before liquid-liquid extraction with dichloromethane, gave better recoveries and repeatability. After single exposure, bromazepam was present in powdered hair at 28 pg/mg and 7-Aminoclonazepam at 22 pg/mg in the first 1-cm segment, while no clonazepam was detectable. This method was applied in two forensic cases. It allowed us to determine bromazepam in urine 3 days after the alleged offense and in cut head hair at a concentration of 6.7 pg/mg only in the 2-cm proximal segment. The other case showed the presence of clonazepam and 7-Aminoclonazepam in urine a few hours after the offense and the presence of 7-Aminoclonazepam at about 3.2 pg/mg in axillary hair 4 months later.