Born near the south side of Chicago, Greg Rzab began playing bass guitar at the age of fifteen practicing for hours to recordings by Jimi Hendrix, Little Walter and Curtis Mayfield. Greg also looked to bassists such as John Paul Jones and Jaco Pastorius for inspiration.

As a teenager he got to see Muddy Waters live and from that time on he constantly began hanging out at the Chicago blues clubs learning all he could and sitting in whenever given the opportunity. When Greg was twenty-one years old, he sat in with Otis Rush and immediately after was asked to play in his regular band which lasted for several years. He also kept busy working with a variety of other great blues legends such as Albert Collins, Luther Allison, Willie Dixon, John Lee Hooker, Hubert Sumlin and Junior Wells.

At a show with Junior, he met and played with Buddy Guy so beginning a twelve year stint in that band. ??Shortly after, Greg got an offer from John Mayall and happily joined him for a European tour in 1999 and 2000. But just as things were going well, Greg accepted the offer of a high profile gig with another of his heroes, Jimmy Page, that resulted in a reluctant departure from John.

After the tour with Jimmy came to an end, Greg was part of the Warren Haynes group 'Gov't Mule' and he also recorded and played with Carlos Santana, Eric Clapton, Jeff Beck, The Allman Brothers Band, Stevie Ray Vaughan and The Black Crowes. At the beginning of 2009, Greg got an offer to work again with Mayall in a new band line-up that was being assembled and was very pleased to accept. Since then he has more than made his mark as a mainstay onstage and in the studio with John.