Gardaí in Dundalk have seized 200 cannabis plants worth an estimated €160,000.
Cannabis herb with an estimated street value of €50,000 was also seized.
It follows the search of a house on the Caste Road in the town this afternoon.
Gardaí say they have uncovered what has been described as a "sophisticated cannabis cultivation grow house" after stopping a car whose occupants were acting suspiciously.
The plants seized were in various stages of growth.
Two men in their thirties have been arrested in connection with the incident, and are being held at Dundalk Garda Station under section 4 of the Criminal Justice Act.