It is important to establish the pattern of suicidal ideation among adolescents with depression and anxiety. This will help the schools prevent possible complete suicide among these groups of adolescents' trough counseling and education. This work is therefore aimed at determining the effects of depression and anxiety on adolescent suicide ideation and factors that predict suicidal ideation among adolescents attending secondary school in southeast Nigeria. A cross-sectional study among 450 secondary school adolescents in Enugu state, Nigeria. Information was obtained using the Columbia suicide severity rating scale and the Hospital Anxiety and Depression Scale (HADS). Chi-square test, correlation analysis and Hierarchical logistic regression were used in the analysis, and the level of statistical significance was determined using a P-value of <0.05. The prevalence of anxiety was 36.4% while that of depression was 30.7%. The prevalence of suicidal ideation was 8.4%. The prevalence of suicidal ideation among adolescents who were <15 years was 8.0% while those who were between 15 - 18 years was 13.5% and those more than 19 years of age was 22.5%. The prevalence of suicidal ideation among adolescents with depression is 21.7% and 78.3 % for those without depression while the prevalence of suicidal ideation among adolescents with anxiety is 20.1% and 79.9 % for those without anxiety. The prevalence of suicidal ideation among the poorest half was 16.4% and 10.2% in the richer half. There was a higher prevalence of suicidal ideation among the urban dwellers (53.3%) than the rural dwellers (46.7%).There was a positive correlation between suicide and age in years and this was found to be statistically significant, (n=450, r=0.107, p=0.023). A significantly higher proportion of respondents who had depression, 21.7% had suicidal ideation when compared with those who were not, (χ 2=12.170, p<0.001). Similarly, a significantly higher proportion of respondents who had an anxiety disorder, (20.1%) had suicidal ideation when compared with those who were not, 9.4%, (χ 2=10.291, p=0.001). The respondents who were 19 years and above had increased suicidal ideation, and the difference in proportions was found to be statistically significant, (χ 2=6.440, p=0.040). A significantly higher proportion of females, 16.6% had suicidal intentions when compared with the males, 7.1%, (χ 2=7.958, p=0.005). There is an increasing prevalence of suicidal ideation among adolescents with a preponderance of older age and female gender. There is a link between depression/anxiety and suicidal ideation. The prevalence of suicidal ideation among the poorest half was higher than that of the richer half. There was a higher prevalence of suicidal ideation among the urban dwellers than the rural dwellers.