Action against driving under the influence of drugs (DUID) often starts with an on-site immunological screening which is not yet developed for new psychoactive substances (NPS). Our aim was to determine the prevalence of NPS in drivers screened positive for a classical illicit drug. Blood samples (n=556) were obtained between January–August 2015 in Belgium. The on-site Drugwipe 5S (Securetec) results and the subjects’ signs of recent drug use were available. Classical illicit drugs were confirmed in blood via LC-MS/MS methods. NPS screening was performed using 2 methods: LC-HRMS and LC-MS/MS. Of the 256 samples yet analysed, NPS were detected in 13 samples (5%) including following substances (n): ketamine (5), methoxetamine (2), diphenidine (2), 5-MeO-DALT (1), 4-AcO-DiPT (1), methiopropamine (1), methedrone (1), α-PVP (1), a mix of 5-MAPB/5-EAPB (1), and AB FUBINACA (1). This preliminary study demonstrates a prevalence of 5%. However, this result should be confirmed and reassessed at the end of our study.