"Aquarius/Let the Sunshine In", sometimes referred to as "The Age of Aquarius" or "Let the Sunshine In", is a medley of two songs from the musical Hair("Aquarius" and "The Flesh Failures (Let The Sunshine In)") written by James Rado, Gerome Ragni, and Galt MacDermot, and released as a single in 1969 by The 5th Dimension. The single held the number one position on the U.S. Billboard Hot 100 for six weeks and was certified Platinum.

The song listed at #57 on Billboard's Greatest Songs of all time.

The recording won the Grammy Award for Record of the Year and Best Contemporary Vocal Performance by a Group at the Grammy Awards of 1970, after it was released on the album The Age of Aquarius.

The song was based on the astrological belief that the world would be entering the Age of Aquarius, an age of love, light and humanity, unlike the then current Age of Pisces. This change was presumed to occur at the end of the 20th century, however major astrologers differ over this. Dates range from 2062 (Dane Rudhyar), 2150 (Neil Mann), 2595 (Hermann Haupt) and 2680 (Shephard Simpson).

"Aquarius/Let the Sunshine In" was ranked thirty-third on the 2004 AFI's 100 Years... 100 Songs.

"Nel blu dipinto di blu (Volare)" · "Mack the Knife" · "Theme from A Summer Place" · "Moon River" · "I Left My Heart in San Francisco" · "Days of Wine and Roses" · "The Girl from Ipanema" · "A Taste of Honey" · "Strangers in the Night" · "Up, Up and Away" · "Mrs. Robinson"

" Aquarius/Let the Sunshine In " · "Bridge over Troubled Water" · "It's Too Late" · "The First Time Ever I Saw Your Face" · "Killing Me Softly with His Song" · "I Honestly Love You" · "Love Will Keep Us Together" · "This Masquerade" · "Hotel California" · "Just the Way You Are"

"What a Fool Believes" · "Sailing" · "Bette Davis Eyes" · "Rosanna" · "Beat It" · "What's Love Got to Do with It" · "We Are the World" · "Higher Love" · "Graceland" · "Don't Worry, Be Happy"

"Wind Beneath My Wings" · "Another Day in Paradise" · "Unforgettable" · "Tears in Heaven" · "I Will Always Love You" · "All I Wanna Do" · "Kiss from a Rose" · "Change the World" · "Sunny Came Home" · "My Heart Will Go On"

"Smooth" · "Beautiful Day" · "Walk On" · "Don't Know Why" · "Clocks" · "Here We Go Again" · "Boulevard of Broken Dreams" · "Not Ready to Make Nice" · "Rehab" · "Please Read the Letter"

"Use Somebody"