In a statement, Detective Senior Sergeant Greg Baird said simultaneous search warrants were executed in the Invercargill and Bluff areas.
Police found 46 cannabis plants, 150 ounces (4.25kg) of high-quality cannabis head, cannabis oil, about $25,000 cash, and MDMA, Baird said.
Those arrested have been charged with a raft of offences, including offering to supply LSD, offering to supply ecstasy, possession of cannabis for supply, and failing to comply with obligations in relation to a computer search.
They have been bailed to appear in the Invercargill District Court.