AIMShort term administration of benzodiazepines (BZD) was found to prolong reaction time (RT) in experimental studies. However, studies on long term BZD use did not always adjust for important confounders and showed inconsistent results. We aimed to identify a possible relationship between long term BZD use and RT in BZD users in this large cross-sectional, observational study. METHODSThe RTs of non-users (n = 2404) were compared with low (n = 288), intermediate (n = 74), and high dose BZD users (n = 57) in the Netherlands Study of Depression and Anxiety (NESDA). RTs were obtained from the Implicit Association Test. Analyses were adjusted for sociodemographic characteristics, health indicators, severity of psychopathology and antidepressant use. RESULTSOf the NESDA participants, 419 subjects (14.8%) used BZDs. A higher dose of BZDs was associated with prolonged RTs (P = 0.01). When comparing the different dose groups, the high dose group, but not the low and medium dose groups, had significantly longer RTs than the non-users. CONCLUSIONSTolerance for the RT prolonging effect of relatively high doses of BZDs does not seem to develop. As prolonged RTs can have adverse consequences in daily life, BZDs should be prescribed conservatively at the lowest possible dose. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Short term benzodiazepine (BZD) use prolongs reaction time (RT).• Although the prevalence of long term BZD use is high, it in unclear whether RT is still affected in chronic use. WHAT THIS STUDY ADDS• High dose BZD use is associated with prolonged RTs in chronic users (independent of psychopathology).• Tolerance for the RT prolonging effect of BZDs does not seem to develop at high doses in chronic users.