On Dec. 18, HMCS Toronto boarded a ship off the east coast of Africa carrying 506 bags of heroin, weighing more than 538 kilograms.
The Canadian Forces calls it the largest heroin seizure in the history of combined maritime forces operations.
The military says the drugs were catalogued and then destroyed.
This latest drug bust comes after HMCS Toronto intercepted and boarded a suspected smuggling vessel in October and seized 154 bags of heroin weighing more than 180 kilograms.
The frigate has made a number of drug seizures while on patrol in the past few months, including seizing 500 kilograms of heroin last March and about 5,950 kilograms of hashish in another boarding incident in May.
HMCS Toronto is on patrol in the region as part of an international effort to curb terrorism and deter piracy on the high seas.