When officers from the Hai Chau District police went into the club on Dong Da Street at midnight, there were hundreds of customers, many high on drugs.
The police found Vo Ngoc Phi, 30, Phan Van Kiem, 23, and some others sitting at three tables and possessing 30.5 tablets of ecstasy and two packs of ketamine.
The officers tested 43 people at these tables and 38 were positive for drugs.
After randomly testing some other customers at the club, they found 26 more drug users.
On Wednesday afternoon, Colonel Tran Phuoc Huong, the local police chief, said Phi, Kiem, To Ngoc Linh, 33, and Ho Nhat Hai, 23, have been detained for questioning about the possession and use of drugs.
The others have been charged with illegal drug use.
Phi claimed to have brought the ecstasy pills there to celebrate his girlfriend's birthday, but she did not turn up.
Phi has been jailed before for drug trafficking, and he completed his sentence only last year.