The Hitch star was admitted to the Cirque Lodge facility in Utah last month (Jan08).
Reports suggested Mendes was battling substance abuse issues.
When she entered rehab, her publicist said: "Eva has been working hard for the past year and made a positive decision to take some much needed time off to attend to some personal issues that, while not critical, she felt deserved some outside professional support."
American magazine Life & Style has confirmed the Latina left the rehab clinic on Wednesday (06Feb08) and boarded a flight to Los Angeles.
The Cirque Lodge has become a leading celebrity refuge in recent months - Lindsay Lohan spent last summer (07) there, rocker Richie Sambora also stayed at the facility last year, and actress Kirsten Dunst has reportedly just checked in.
Source: WENN