A statement from the Turkish health ministry on Monday says powdery substances sent to the consulates last week tested negative for anthrax, ricin, botulism, tularemia and a plague bacteria.
However, it says more advanced tests are being conducted.
The Department of Foreign Affairs says the Canadian consulate in Turkey's largest city would remain closed Monday as a precaution but that all staff were safe and accounted for.
The consulate was shut down on Friday after it received a package containing a suspicious yellow powder.
Staff members who came into contact with the powder were sent to hospital but a Foreign Affairs spokeswoman said Monday that all of them have now been released.
Similar packages were also sent to the German, Belgian, French and American consulates in Istanbul on Friday, and authorities say the Hungarian Consulate in the city also received a package on Monday.
Foreign Affairs officials say Canadians in the area who require consular assistance should contact the consulate in Ankara.
— With files from The Associated Press