His booking agent, Jim Douglas, says Montrose died Saturday at his home in Millbrae, Calif. He was 64.
Douglas says Montrose had been in declining health for some time, battling prostate cancer and what Douglas termed "personal demons."
In addition to forming his own band in 1973, Montrose performed with a number of rockers, including Sammy Hagar, Herbie Hancock, Van Morrison, Boz Scaggs and the Edgar Winter Group. Douglas says Montrose was working on releasing a DVD and starting a tour that would have taken him across the U.S.
Montrose is survived by his wife, Leighsa, as well as a son, a daughter and five grandchildren.
