Abstract Background Adolescent suicidal behaviour is a neglected public health issue especially in middle- and low-income countries. Informed policy decision-making on suicidal behaviour will need reliable information on the prevalence and correlates of suicidal ideation which is a determinant of suicidal behaviour. Methods We estimated the prevalence and associated factors of suicidal ideation among school-going adolescents using data from the Global School-Based Health Survey conducted in 2004 in Guyana. Results Of the 1197 respondents, 18.4% (14.9% males and 21.6% females)reported having seriously considered committing suicide in the last12 months. Males were less likely to seriously consider committingsuicide than females (OR = 0.45; 95% CI [0.30, 0.67]). Subjects whoreported having been bullied were more than twice as likely tocontemplate committing suicide as those who had not been bullied (OR = 2.46 [1.71, 3.54]). History of depression was positivelyassociated with suicidal ideation (OR = 2.67; 95% [1.87, 3.81] whilehaving close friends and understanding parents were negativelyassociated with suicide ideation (OR = 0.51; 95% CI [0.28, 0.94] and OR = 0.51; 95% CI [0.35, 0.76] respectively). Conclusion Suicidal ideation is a significant public health issue among in-school adolescents in Guyana that requires attention. The design, implementation and evaluation of suicidal behaviour interventions should incorporate our knowledge of these associated factors.