"As so many other recovering alcoholics know, overcoming the disease can be a long and incredibly difficult process," Vargas said in a statement. "I feel I have let myself, my co-workers and most importantly my family down and for that I am ashamed and sorry."
The ABC News reporter entered the treatment facility over the weekend. Vargas first checked in to a rehab in November 2013 for alcohol abuse, an addiction she said began as a coping mechanism.
The 20/20 anchor's network is standing behind her again as she focuses on getting better.
"We look forward to having her back at ABC News when she feels ready to return," ABC News said in a statement, according to People.