Cocaine and Benzodiazepines were found when gardaí executed four search warrants in homes in Swinford and Kilkelly over the weekend.
The Mayo Divisional Drugs Taskforce was joined by the Garda National Dog Unit on Saturday as they carried out searches of residential properties in the East Mayo area.
No illegal substances were found in the Kilkelly. However, substances, believed to be cocaine and benzodiazepines were discovered in three separate properties in Swinford.
In a premises in Swinford two males, aged 30 and 29, were found in possession of a small quantity of drugs, believed to be cocaine. An unlicenced firearm was also seized.
In a second house a 33-year-old female was found with a quantity of benzodiazepines and in a third residence a 21-year-old male was found with a small quantity of benzodiazepines.
Garda investigations are continuing and files are being prepared for the Director of Public Prosecutions (DPP).