Police are looking for the other 16.
Local reports say that around 100 drug users at the rehab center in the Mekong Delta province of Dong Thap, 143 kilometers (88 miles) to the southwest of Ho Chi Minh City, smashed through doors and fought with guards on Wednesday night.
Thirty-eight of them broke the center’s gates and escaped.
Hundreds of police officers were dispatched to the scene to ensure security and track down the escapees.
Bui Thanh Nhon, director of Dong Thap's department of social affairs, said Thursday that 22 drug addicts have been returned to the facility and police are still looking for the remaining 16 inmates.
Wednesday’s breakout took place just a month after 200 drug users busted out of at a rehab center in Tien Giang Province, a two-hour drive to the west of Dong Thap.
The center in Dong Thap is home to around 243 inmates, including 15 women.
Vietnam has 132 rehab centers in total, and there are around 220,000 drug addicts on official records.
Several breakouts have occurred in recent years at rehab centers.
Vietnam treats drug addiction as a “social evil” that can be cured with abstinence and re-education.
Following international criticism, the government established a timeframe in 2013 to gradually replace compulsory detention centers with community-based, voluntary treatment regimens.
The transition, however, has proven tricky given inconsistencies in the legal system, the widely-held belief that drug addiction stems from moral failure, and the lack of competent doctors, therapists and equipment.