Gardaí arrested two women from a vehicle in the Castlebar area on Wednesday afternoon.
The two, aged in their twenties, were travelling with a child and were found in possession of suspected drugs.
One of the women was also arrested on suspicion of drunk driving as well as under section 15 on suspicion of the sale and supply of illegal drugs.
They were taken to Castlebar Garda Station for questioning.
A file will now be prepared for the DPP.