['We studied failure and delay in making initial treatment contact after the first onset of a mental or substance use disorder in Mexico as a first step to understanding barriers to providing effective treatment in Mexico.', 'Data were from the Mexican National Comorbidity Survey (2001-2002), a representative, face-to-face household survey of urban residents aged 18 to 65 years. The age of onset for disorders was compared with the age of first professional treatment contact for each lifetime disorder (as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition).', 'Many people with lifetime disorders eventually made treatment contact, although the proportions varied for mood (69.9%), anxiety (53.2%), and substance use (22.1%) disorders. Delays were long: 10 years for substance use disorders, 14 years for mood disorders, and 30 years for anxiety disorders. Failure and delay in making initial treatment contact were associated with earlier ages of disorder onset and being in older cohorts.'] Do delay of first treatment of mental and substance use disorders in Mexico?