Gardaí carried out a search of a house in the Bangor Erris area of Ballina on Sunday.
A small amount of suspected drugs consisting of tablets and white powder were discovered along with other drug related paraphernalia.
The seized drugs will now be sent for analysis.
A man, aged in his 30s, was arrested at the scene and taken to Belmullet Garda Station.
He has since been released without charge.
Gardaí say investigations into the seizure are continuing.