Sex differences in suicide rates and suicide methods was compared among adolescents in South Korea, Japan, Finland, and the United States. This study analyzed suicide rates and suicide methods of adolescents aged 15-19 years in four countries, using the World Health Organization mortality database. Among both male and female adolescents, the most common method of suicide was jumping from heights in South Korea and hanging in Japan. In Finland, jumping in front of moving objects and firearms were frequently used by males, but not by females. In the United States, males were more likely to use firearms, and females were more likely to use poison. The male to female ratio of suicide rates was higher in the United States (3.8) and Finland (3.6) than in Korea (1.3) and Japan (1.9). Sex differences in suicide methods may contribute to differences in the suicide rates among males and female adolescents in different countries.