Revenue officers at Portlaoise Mail Centre seized 7.1kg of herbal cannabis with an estimated street value of €142,000 today.
The drugs were discovered concealed in two parcels from America and Canada and were destined for separate addresses in Dublin city centre.
The discovery came after what Revenue described as "routine profiling".
In a separate incident, ecstasy with an estimated street value of €4,500 was seized at Dublin Mail Centre.
The ecstasy was discovered in two packages from the Netherlands with the assistance of Revenue detector dog Bailey.
The packages were destined for addresses in Galway and Roscommon.
Revenue say the seizures are part of their ongoing operations targeting drug importations.