BACKGROUND Studies directed on suicidal behavior in North African adolescents are rare. This study was conducted to estimate the prevalence of suicidal thoughts and attempts among high school students in Tunisia and to determine factors associated with this suicidal behavior. METHODS This is an analytical cross-sectional study composed of a population containing 821 high school students obtained through cluster sampling. The participants completed a pre-established form related to socio-demographic characteristics and anxiety symptoms, the Suicide Behavior Questionnaire-Revised, the Beck depression scale, and the Rosenberg self-esteem scale. RESULTS The mean age of the adolescents was 17.7±0.97 years. Prevalence of suicidal behavior was 26.9% for brief passing suicidal thoughts, 9.6% for serious suicidal thoughts, and 7.3% for suicide attempts. Six determining factors of suicidal behavior were found: female gender (OR=2.56 (1.32-4.95); p= 0.005), personal history of depression (OR=2.29 (1.38-3.80); p=0.001), tobacco smoking (OR=3.59 (1.61-8.01); p=0.002), current depression symptoms (OR=5.50 (2.14-14.11); p<0.001), history of non-suicidal self-injurious behavior (OR= 3.16 (2.05-4.86); p<0.001), and low self-esteem (OR=2.74 (1.71-4.38); p<0.001). CONCLUSIONS Suicidal ideation and attempts are frequent among Tunisian adolescents and represent a serious public health problem. An urgent national prevention program is required.