Following a series of searches as part of Operation Tara, Gardai arrested five persons and seized drugs worth about €350,000.
A raid on a house in Dundalk, Co Louth, discovered €200,000 in cannabis.
Gardai in Swords, Co Dublin, seized €110,000 in cannabis.
Following the second search of a house in Blanchardstown, Dublin, a fresh batch of cannabis worth €38,000 was recovered.
The five persons are still being held at the Ballymun and Blanchardstown Garda Stations.
“Tackling the supply of drugs to communities will continue to be a priority for Divisional Drug Units and all members of An Garda Sochána, working in partnership with local communities to keep people safe,” Assistant Commissioner Angela Willis said following the operation.
“This seizure of a substantial amount of illicit drugs along with paraphernalia utilised to facilitate its distribution is significant in that regard.”