Seven men and one woman were detained in a series of dawn raids at addresses in Burnley on Wednesday morning (May 11).
The suspects – aged between 20 and 31 – were all arrested on suspicion of drug offences.
They remained in custody for questioning on Wednesday afternoon.
Police said the raids followed a lengthy investigation into the supply of Class A drugs in Burnley and East Lancashire.
Det Insp Tom Edmondson, of East Police, said: “We are committed to taking the fight to criminals and disrupting drug-dealing activity and protecting vulnerable members of society in order to keep our streets safe.
“I would encourage anyone concerned about criminal activity in their area to contact the police, knowing that we will act on that information and take the appropriate action.”
Anyone with concerns about drug-dealing or any other criminal activity in their area can call police on 101 or 999 in an emergency.
Crimestoppers can also be contacted anonymously on 0800 555111 or online at crimestoppers.org.