Police raided the house in Nimes Street, Fishwick, yesterday and found more than 100 bags of cannabis.
As well as the drug, which was packaged up in snap bags ready to be distributed, they also found £2,500 in cash at the property.
The raid was lead by PC Brown of the local neighbourhood policing team, who had spent the last few weeks gathering intelligence on the address.
Sergeant Haworth of Preston Police said: "Both occupants of the address were subsequently arrested and taken to custody. An excellent result."