BackgroundSuicidal ideation and attempts usually occur during adolescence time, and living in war- affected area make the problem more predominate and severe. To the best of our knowledge, there were no studies done among high school students who live in war affected areas in Ethiopia.ObjectiveWe assessed the prevalence and factors associated with suicide ideation and suicide attempts among high school students of war- affected area at Woldia town, Northeast, Ethiopia.MethodsSchool based cross-sectional study was conducted from May 23 to June 08, 2022.Data were collected from high school students in Woldia town, Ethiopia. Pretested, self-administered Amharic-language questionnaire was used to collect the data. Bivariable and multivariable logistic regression was used to identify the independent factors associated with suicide ideation and attempt.ResultsA total of 668 of the 707 sampled students participated in the study (94.5% response rate). The prevalence of suicidal ideation and attempts among high school students in Woldia town was 16.29% and 12.87%, respectively. In the multivariable analysis, poor social support(AOR = 2.86, 95% CI:1.49, 5.46), posttraumatic stress disorder (AOR = 2.15, 95% CI:1.20, 3.85), family history of suicide(AOR = 3.94, 95% CI:2.21, 7.04), anxiety(AOR = 3.45, 95% CI:1.72, 6.89), and depression (AOR = 2.31, 95% CI:1.24, 4.33) were factors significantly associated with suicide ideation, and poor social support(AOR = 2.75, 95% CI:1.38, 5.47), depression (AOR = 4.27, 95% CI:2.10, 8.67) and being a female sex (AOR = 2.12, 95% CI:1.22, 3.69) were factors significantly associated with suicidal attempt.Conclusions and recommendationsThis study revealed that at least one in six and one in eight of the students had suicidal ideation and attempt, respectively. Therefore, we recommend that Ministry of Education shall work with Ministry of Health to extend and implement mental health services in high schools and provide social support to those students who need the services in order for the prevention of suicidal ideation and attempts.