Almost 48,000 cigarettes have been found following separate operations in Cavan and Dublin.
Some 41,200 unstamped cigarettes were found in Co Cavan on Tuesday.
It was part of an an intelligence-led operation by Revenue officers.
They seized the unstamped cigarettes following a search under warrant of a residential property.
The detection was made with the assistance of Revenue detector dog, Bill.
The unstamped cigarettes - branded 'NZ', 'West' and 'Pall Mall' - had a retail value of €26,000, representing a potential loss to the exchequer of over €20,730.
Revenue has said investigations are ongoing with a view to prosecution.
Separately last Friday, Revenue Officers in Dublin Port seized 6,600 cigarettes and 165 litres of alcohol as a result of routine operations.
The discovery followed the search of a vehicle which arrived from Romania via Holyhead.
The seized cigarettes - branded 'Winston', 'Kent' 'Marlboro' and 'Pall Mall' - along with the alcohol had a combined retail value of €9,354 and represented a potential loss to the exchequer of €6,588.