St George Illawarra, Newcastle and Gold Coast face fines totalling $350,000 as the NRL launches a major clampdown on alleged breaches of concussion protocols.
The Dragons were slugged with a $100,000 fine after Josh Dugan appeared to cop a head knock in Sunday's win over Cronulla but was allowed to play on.
The Knights were slugged for the same amount after Brendan Elliot stayed on after copping a swinging arm from Hymel Hunt while the Titans are facing a $150,000 sanction over the treatment of Kane Elgey, Joe Greenwood and Ryan Simpkins.
The clubs have five days to respond to the breach notices.
"These are, by far, the heaviest fines ever proposed by the game for concussion breaches," NRL CEO Todd Greenberg said.
"That is how seriously we take it."