(エスオーエス), Esu Ō Esu) is a song Yū Aku and Shunichi Tokura wrote for Japanese idol duo Pink Lady.

Because its sound effect might be mistaken for genuine Morse code, the intro of the track was omitted occasionally during radio airplay.

Led by commercial success of its predecessor "Pepper Keibu" which reached the number-4 on the Japanese Oricon chart, "S.O.S" climbed the top of the country's hit parade three months after its release.

The single remained on the chart for 38 weeks, selling approximately 650,000 copies.

All lyrics are written by Yū Aku; all music is composed and arranged by Shunichi Tokura.