Mickey & The Hartbeats played a handful of shows at The Matrix in 1968 and were essentially The Grateful Dead without Bob Weir & Pigpen McKernan.

In October 1968 Bob Weir and Pigpen were kicked out of the Grateful Dead for their lack of commitment to the project and the practice sessions. The remaining members of the band played a few shows at the Matrix in San Francisco at the end of that month, billed as Mickey And The Hartbeats. Various friends would sit in on these shows. The act mostly consisted of Grateful Dead songs without the lyrics. Both Weir and Pigpen eventually rejoined the band in August 1969, and they were able to survive as the Grateful Dead.