Samoa
21 years of age; universal
San Marino
18 years of age; universal
Sao Tome and Principe
18 years of age; universal
Saudi Arabia
21 years of age; male
Senegal
18 years of age; universal
Serbia
18 years of age; universal
Seychelles
17 years of age; universal
Sierra Leone
18 years of age; universal
Singapore
21 years of age; universal and compulsory
Slovakia
18 years of age; universal