OBJECTIVE To develop a risk index of suicide attempts in the last 12 months among people with suicide ideation. METHODS Cross-sectional study. Data came from the National Addictions Survey 2008. The risk index was made up by age, marital status, religion, occupation, area of the country in which they live, immigrant to the United States, alcohol and drug consumption, depression symptoms, behavioral problems and a history of sexual abuse. RESULTS We found a monotonic relationship between the increase in risk factors and the existence of a plan and the risk, with an odds ratio over 2.07 up to 152.19. The area under the curve is quite high, with a value of 0.844, very close to 1. CONCLUSIONS The use of this index may help prevent patients from further developing their suicide ideation process and may prevent a suicide attempt of uncertain consequences, including death.