Mephedrone is also known as MCAT and bubbles
Seventeen people tested positive for drugs during a weekend crackdown in Aberdeen, police have said.
Officers using a special scanner tested more than 600 revellers for cocaine, MDMA and mephedrone at pubs and clubs in the city.
Mephedrone - commonly known as MCAT or bubbles - is a legal high recently banned in Aberdeen bars and clubs.
A total of five bags of what was suspected to be mephedrone were recovered.
Grampian Police Sgt David Bremner, who led the operation for the city centre unit, said: "This was a highly successful operation and underlines the force's zero tolerance approach to drugs."
He added: "Although mephedrone is not yet a controlled substance, its effects are similar to other controlled stimulants like cocaine.
"The effects of mephedrone are unpredictable, especially when combined with other drugs or alcohol. Just because it's legal doesn't make it safe."
Mephedrone is sold on the internet as a plant feeder.