Dedicated to Joe Gillis on the occasion of his 75th birthday Key words, root systems, constant term identities, hypergeometric summation AMS(MOS) subject classifications. 31, 05A We will prove the following theorem. THEOREM Let m and n be integers and x, y and z commuting indeterminates; then the constant term of the Laurent polynomial F(x, y, z,: [(1-)(1-)(1_)]m[(1-xY)(1-iz)(1-x Y-z) ] " C(m,n)= (3m + 3n)!(3n)!(2m)!(2n)! (2m + 3n) !(m + 2n) !(m + n)!m!n!n! This is the G2 case of Macdonald's Root System-Dyson conjecture (see [6, Conjecture 2.3, and (c), p. 994]; see also Morris [7]). Macdonald [6] showed how Selberg's integral [8] (see [1] for Aomoto's recent brilliant proof) implies his conjecture for all the so-called classical root systems. We will follow the same route and show how the G2 case follows from a corollary of *