A Government crackdown on head shops selling psychoactive substances appears to have been a success with only 19 now in operation, according to garda figures.
And officers are satisfied from regular monitoring of the outlets that none of them is suspected of the sale or supply of the harmful products.
At the height of the health scare earlier this year over the sale of legal "highs", the number of head shops had risen to 102 around the country.
But the number still in business has plummeted to less than a fifth of the figure last spring, according to Justice Minister Dermot Ahern.
He said he had been informed by garda authorities that the Criminal Justice (Psychoactive Substances) Act, which came into effect towards the end of August, had an immediate positive impact in vastly reducing the number of head shops nationwide .
He confirmed none of the remaining shops had, to date, been found or suspected of the sale or supply of the substances, which are now illegal.
Ireland became the first country in Europe to bring in a "catch all" law rather than focusing on specific substances.
The law is operated in tandem with controls introduced by Health Minister Mary Harney, who published a list of 200 banned products.
The number of shops dropped to 36 after the list was implemented but grew again to 48 when new substances emerged on their shelves.
But when the legislation was enacted, more shops began to shut down as gardai pledged to use their new powers to regularly check the outlets.
The could also now make test purchases of the items for sale, to determine if they were illegal or unfit for human consumption.
Under the act, the owner of the premises must prove the products are not harmful or prohibited by the legislation.
Gardai also have the power to serve a prohibition notice on a shop owner and if the person does not comply with the notice, the garda officer can then apply to the district court to shut down the premises.
Failure to comply with a prohibition notice is a criminal offence and could result in a maximum penalty of five years' imprisonment.
A prosecution will be treated as a civil rather than a criminal issue, which means the burden of proof will be on the balance of probabilities rather than beyond reasonable doubt.
The legislation also contains widespread search and seizure powers for garda investigating offences linked to the indoor cultivation of cannabis.