Although anxiety is one of the most prominent psychiatric complaints of methamphetamine (MA) users, little is known about the association between anxiety disorders and treatment outcomes in this population. Using data from 526 adults in the largest psychosocial clinical trial of MA users conducted to date, this study examined psychiatric, substance use, and functional outcomes of MA users with concomitant anxiety disorders 3 years after treatment. Anxiety disorders were associated with poorer alcohol and drug use outcomes, increased health service utilization, and higher levels of psychiatric symptomatology, including suicidality. Addressing anxiety symptoms and syndromes in MA users may be helpful as a means of optimizing treatment outcomes.