The effect of atomic alignment on CN (B-2 Sigma(+)) formation has been studied in the reaction of oriented Ar (P-3(2)) with (CX3CN)(2) (X = H, D). The reaction cross-section for each magnetic M'(J) substate in the collision frame sigma(vertical bar M')(vertical bar)(H(D),d)(J) relative to the cross- section sigma(0)(H,m) in the CH3CN reaction was determined to be sigma(0)(H,d)/sigma(vertical bar 1 vertical bar)(H,d)/sigma(vertical bar 2 vertical bar)(H,d)/sigma(0)(D,d)/sigma(vertical bar 1 vertical bar)(D,d):/sigma(vertical bar 2 vertical bar)(D,d) = 0.87/1.00/0.98/1.58/1.93/1.78. A notable deuterium isotope effect was observed. In contrast with the monomer reactions, a significant decrease of sigma(0)(H(D),d) relative to the other cross-sections of sigma(vertical bar M')(vertical bar)(H(D),d)(J) was observed.