A cross sectional study quantified the prevalence of suicidal ideation among university students less than 18 years old and determined variables associated with suicidal ideation. One hundred and ninety-seven students from the National University of Colombia in Bogota were selected by a random stratified sampling. The instrument applied for the measurement of risk factors was the psychiatric interview-approach. The statistical analysis included description of variables, estimation of prevalence by population and social stratum, bivariate analysis and logistic regression to evaluate associated factors. A prevalence of 4.4% of suicidal ideation was found at the time of the interview and 13% during the past year. Suicide ideation and suicide attempts were more frequent in women. The prevalence of depressive disorders was higher than that reported for the general population in the same age group. Childhood abuse was related with psychiatric disorders and with suicidal ideation. Recommendations for the clinical evaluation of suicidal-patients are provided.