|Origin||Melbourne, Victoria, Australia|
|Associated acts||Billy Thorpe & the Aztecs, Sha Na Na, Blackfeather|
|Past members||see personnel list below|
MacKenzie Theory was an Australian jazz rock group formed in September 1971 in Melbourne. Lead guitarist, Rob MacKenzie, and electric viola player, Cleis Pearce were the mainstays. They recorded two albums, Out of the Blue (1973) and Bon Voyage (1974) for Mushroom Records before disbanding in May 1974. Out of the Blue peaked at No. 19 on Go-Set's Australian Albums chart. In the 1990s, MacKenzie was a member of United States rock'n'roll revival act, Sha Na Na.
MacKenzie Theory was formed in Melbourne by lead guitarist, Rob MacKenzie, with bass guitarist Mike Leadabrand and drummer Andrew Majewski in September 1971. At this time Mackenzie also met electric viola player Cleis Pearce at a concert in Sydney, while he was filling in with another group, and he was so impressed with her playing that he immediately invited her to join, even though she had no previous experience of playing rock or improvised music. Previously, MacKenzie had been a member of Leo and Friends, and King Harvest. MacKenzie Theory played instrumental jazz rock with elements of John Coltrane, King Crimson, Mahavishnu Orchestra and Santana. At early gigs they supported other artists including, Band of Light, Billy Thorpe & the Aztecs, Chain, Madder Lake or Spectrum.
They performed at the inaugural Sunbury Pop Festival in January 1972 and at the second festival in January 1973. Their track, "New Song And", was included on the triple live album, The Great Australian Rock Festival Sunbury 1973 which appeared on Mushroom Records in April. Their debut album, Out of the Blue, recorded live in the studio, was issued in July, and it peaked at No. 19 on Go-Set's Australian Albums chart in August. During September, Leadabrand and Majewski left and were replaced by Paul Wheeler (ex-Billy Thorpe & the Aztecs) on bass guitar and Greg Sheehan (ex-Blackfeather) on drums; pianist, Peter Jones joined.
MacKenzie Theory appeared at Sunbury again in 1974 and "Supreme Love" appeared on Highlights of Sunbury '74 Part 2. They disbanded by mid-year before MacKenzie and Pearce travelled to the United Kingdom, their final appearance on 15 May was recorded and released as a live album, Bon Voyage by Mushroom Records, although this was reportedly released against the wishes of Mackenzie, who felt that the performance captured on the album was below-par for the group.
In the 1980s Cleis Pearce performed and recorded with the Sydney-based jazz ensemble Women & Children First, led by saxophonist Sandy Evans. Pearce now lives, composes, teaches and makes art in the Byron Bay area of NSW and has been an artist in residence with Southern Cross University.
- Rob MacKenzie – guitar (1971–1974)
- Mike Leadabrand – bass guitar (1971–1973)
- Andrew Majewski – drums (1971–1973)
- Cleis Pearce – electric viola (1971–1974)
- Paul Wheeler – guitar (1973–1974)
- Greg Sheehan – drums (1973–1974)
- Peter Jones – piano (1973–1974)
- Out of the Blue (1973)
- Bon Voyage (1974)
- McFarlane, Ian (1999). "Whammo Homepage". Encyclopedia of Australian Rock and Pop. St Leonards, NSW: Allen & Unwin. ISBN 1-86508-072-1. Archived from the original on 5 April 2004. Retrieved 9 April 2011. Note: Archived [on-line] copy has limited functionality.
- Spencer, Chris; Zbig Nowara, Paul McHenry with notes by Ed Nimmervoll (2002) . The Who's Who of Australian Rock. Noble Park, Vic: Five Mile Press. ISBN 1-86503-891-1.  Note: [on-line] version of The Who's Who of Australian Rock was established at White Room Electronic Publishing Pty Ltd in 2007 and was expanded from the 2002 edition. As from, September 2010 the [on-line] version shows an 'Internal Service Error' and was no longer available.
- McFarlane, 'MacKenzie Theory' entry. Archived from the original on 23 August 2004. Retrieved 5 May 2011.
- Kimball, Duncan; Pearce, Cleis (2002). "MacKenzie Theory". Milesago: Australasian Music and Popular Culture 1964–1975. Ice Productions. Retrieved 5 May 2011.
- "Search results for "MacKenzie Theory"". Go-Set (Waverley Press). Retrieved 28 April 2011. Note: Go-Set published its national charts from October 1966 until August 1974.
- Cashmere, Paul (18 December 2009). "MacKenzie Theory Remastered". Undercover News (Undercover Network Pty Ltd). Retrieved 5 May 2011.
- "Who's Who of Australian Rock / Compiled by Chris Spencer, Zbig Nowara & Paul McHenry". catalogue. National Library of Australia. Retrieved 28 April 2011.