The performance of eight on-site oral fluid drug screening devices was studied in Belgium, Finland and the Netherlands as a part of the EU-project DRUID. The main objective of the study was to evaluate the reliability of the devices for testing drivers suspected of driving under the influence of drugs (DUID). The performance of the devices was assessed by their ability to detect substances using cut-offs which were set at sufficiently low levels to allow optimal detection of positive DUID cases. The devices were evaluated for the detection of amphetamine(s), cannabis, cocaine, opiates and benzodiazepines when the relevant test was incorporated. Methamphetamine, MDMA and PCP tests that were included in some devices were not evaluated since there were too few positive samples. The device results were compared with confirmation analysis results in oral fluid. The opiates tests appeared to perform relatively well with sensitivity results between 69 and 90%. Amphetamines and benzodiazepines tests had lower sensitivity, although the DrugWipe test evaluated was promising for amphetamine. In particular, it is evident that the cannabis and cocaine tests of the devices still lack sensitivity, although further testing of the cocaine tests is desirable due to the low prevalence and low concentrations encountered in this study.