Even with the most sophsticated tests, the xanax will be out of your system in 3 days max. Please try to stay away from xanax if possible. They are more addicting than almost any drug out there. You can become a full blown benzo addict in the blink of an eye. The half life of Xanax is 4-6 hours, compared to the half-life of Valium which is almost 200 hours.