Occult cardiovascular disease is the leading cause of sudden death in young athletes and strategies to prevent this tragic event have become topical worldwide. It is critical to distinguish trainingrelated electrocardiography (ECG) findings from those suggestive of an underlying pathological disorder. Black ethnicity has been reported as an independent predictor of abnormal ECG findings among athletes compared to other ethnicities. This study sought to contribute to the existing body of knowledge regarding the ECG characteristics of young adolescent athletes of Nigerian origin. The aim was to determine the electrocardiographic patterns in secondary school athletes aged 10 to 18 years and matched controls, to determine the prevalence of abnormal ECG findings in both groups as well as examine the relationship between ECG findings and three selected variables namely age, sex and body mass index. This cross sectional study was carried out over an eight month period between November 2014 and July 2015. A total of 360 secondary school students (180 athletes and 180 matched controls) were recruited from six secondary schools in the Lagos Metropolis. Participants were evaluated using an interviewer-administered questionnaire to obtain relevant cardiovascular history and information on sporting disciplines; after which physical examination was carried out and resting 12 - lead ECG was performed for each participant using the Sonoscape SE 508 3 channel ECG recorder. ECG tracings were interpreted using standard guidelines.