And the number using banned substances behind bars is rising.
Between November 2012 and February this year, 162 people tested positive for drugs – 23 per cent of those who were tested.
That compares to 149 people – 20 per cent – the previous year. The figures have led to calls for action to tackle drug use in jails.
Scottish Conservative justice spokeswoman Margaret Mitchell said: “The regime inside our prisons is nothing like as robust as it should be.”
Scottish Liberal Democrat justice spokeswoman Alison McInnes MSP added: “It serves no-one if offenders come out of prison with more problems than they came in with.”
And Graeme Pearson MSP, Scottish Labour justice spokesman, said: “The number of inmates leaving prison with drugs in their system is unacceptably high and Kenny MacAskill needs to take urgent action on this.”
The Scottish Prison Service highlighted an increase in sniffer dogs as one of many measures aimed at tacking drugs.
A spokesman said: “We are not being complacent, we are making terrific efforts to intercept the supply of drugs and also support people to make positive life choices, to help them break their addiction problems.”
A Scottish Government spokeswoman said: “Getting these people into treatment early is the key to supporting them into recovery”