An UPLC-TOF-MS method for simultaneous screening and quantification of 52 drugs in hair was developed and validated. The selected drugs represent the most common classes of pharmaceuticals and drugs of abuse such as amphetamines, analgesics, antidepressants, antipsychotics, benzodiazepines, cocaine, ketamine and opioids. Hair samples were extracted with methanol:acetonitrile:ammonium formate (2 mM, 8% acetonitrile, pH 5.3) overnight at 37 degrees C. The target drugs were separated and quantified using a Waters ACQUITY UPLC coupled to a Waters Micromass LCT Premier XE Time-of-Flight mass spectrometer. Total chromatographic run time was 17min. The data were treated with the MassLynx software ChromaLynx XS and QuanLynx for automated identification and quantification, respectively. The limits of detection ranged from 0.01 to 0.10 ng/mg using a 10-mg hair sample and the limit of quantification was 0.05 ng/mg for 87% of the analytes. A good linear behaviour was achieved for most of the analytes in the range from LOQ to 10 or 25 ng/mg except for the amphetamines. The method showed an acceptable precision and trueness, since the obtained CV and BIAS values were