He joined representatives from Police Scotland, Trading Standards and the Home Office for discussions on how to deal with the increasing problems posed by new psychoactive substances.
As the summer music festival season approaches, Mr MacAskill warned: "Just because they are legal doesn't mean they are safe. Just because they are not illegal doesn't mean they can't cost you your life or cause other serious harm."
Legal highs were involved in 47 deaths in 2012 and hundreds more people across Scotland have been admitted to hospital in the past five years.
Substances sold as legal highs are produced to have similar effects to drugs such as ecstasy but they fall outside the UK Government's misuse of drugs laws.