Hot Rats is the second solo album by Frank Zappa. It was released in October 1969. The album consists of six songs, five of which are instrumental. Willie the Pimp features a short vocal by Captain Beefheart (Don van Vliet). It was Zappa's first recording project after the dissolution of the original Mothers of Invention. Because it focuses on long instrumental jazz-like compositions with extensive soloing, the music sounds very different than earlier Zappa albums which featured short songs with satirical vocal performances. It features none of the Mothers, save Ian Underwood, who was also the primary collaborator and sideman. In his original sleeve notes Zappa described the album as "a movie for your ears."
1. Peaches en Regalia - 3:58
2. Willie the Pimp - 9:25
3. Son of Mr. Green Genes - 8:58
1. Little Umbrellas - 3:09
2. The Gumbo Variations - 12:55
3. It Must Be a Camel - 5:15
* Frank Zappa – Guitar, percussion, octave bass
* Ian Underwood – organ, clarinet, flute, piano, saxophone
* Max Bennett – bass on all tracks except "Peaches en Regalia"
* Captain Beefheart – harmonica, vocals on "Willie the Pimp"
* John Guerin – drums on "Willie the Pimp", "Little Umbrellas" and "It Must Be a Camel"
* Don "Sugarcane" Harris – violin on "Willie the Pimp" and "The Gumbo Variations"
* Paul Humphrey – drums on "Son of Mr. Green Genes" and "The Gumbo Variations"
* Shuggie Otis – bass on "Peaches en Regalia"
* Jean-Luc Ponty – violin on "It Must Be a Camel"
* Ron Selico – drums on "Peaches en Regalia"
* Lowell George - guitar (uncredited)
* Harvey Shantz – Snorks