"Good-bye Baby" is a song recorded by K-pop girl group Miss A for their debut studio album A Class. "Good-bye Baby" topped the Gaon Digital Chart for two weeks and became one of the best-performing singles of 2011.
On July 11, 2011 Miss A first teased their comeback nine months after their second single album Step Up, for July 18, 2011, in which the title song "Good-bye Baby" was symbolically written. On July 18, 2011, both the music video for "Good-bye Baby" and their first studio album A Class were released.
"Good-bye Baby" lyrics were written by Park Jin-young and composed by Park Jin-young and Shim Eun-ji. The song is composed in the key G-sharp minor and has 138 beats per minute and a running time of 3 minutes and 46 seconds. "Good-bye Baby" captured the ears of music fans at once with a powerful hip-hop rhythm and acoustic shuffle soul in the story of a woman who relentlessly abandons a flirting man.
On July 21 2011, Miss A held their first comeback stage for the song on Mnet's M Countdown they also performed on M Countdown on July 28. Miss A performed on KBS's Music Bank on July 29 and SBS's Inkigayo on July 31.