Quantum interference effect (QIE) in rotational energy transfer within CO (A(1)Pi, v = 0/e(3)Sigma(-), v = 1) mixed states in collision with HCl are observed with the interference phase angle theta(ST) of 101degrees and 110degrees for DeltaJ = +/-1 transition, respectively, from the initial J = 12 and 13 states. In comparison with the previous similar experiments with He et al. as collision partner, which all give a theta(ST) < 90&DEG;, the interference for a same CO transition in collision with HCl changes from constructive to destructive or the reverse since COS 0(ST) becomes negative. The bigger OST May be explained by the long-range dipole-dipole interaction of proportional to R-3. The physical significance Of θ(ST) is discussed in some details. © 2004 Elsevier B.V. All rights reserved.