BACKGROUND: Suicide attempt among adolescents is a public health problem around the world. The risk of recurrence is high: about 30 % of adolescents. New ways to prevent suicide attempt recurrence being developed for adult suicide attempters include maintaining contact with them, and results are encouraging. METHODS/DESIGN: The MEDIACONNEX study will be a simple blinded, parallel-group, multicenter randomised controlled trial. It will compare usual care alone to a program based on usual care plus short message service (SMS) provided to adolescents who attempt suicide and who receive treatment in pediatric and adolescent psychiatry units at hospitals in eastern France. Adolescents will be recruited over an 18-month period. The intervention will be based on the SMS, involving personalized and evolving text messages, sent on days 7 to 14 and months 1, 2, 4 and 6 after the SA. The primary endpoint will be the recurrence of an SA, with an assessment during 12 months. Secondary endpoints will be the evolution of 1) social networks, 2) depression and 3) health-related quality of life, with an assessment at inclusion and at 6 months. DISCUSSION: This paper describes the design of MEDIACONNEX, which will assess the effectiveness of an SMS program for adolescent suicide attempters on SA recurrence. This program will be easy to reproduce and inexpensive. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov (no. NCT02762734 ) on March 2016.