  We show that for a large class of d=4 N=2 conformal field theories the 1/N
correction to the chiral anomaly of the U(1) R-current can be shown to arise
from the D7-branes present in the dual orientifolded orbifold string theories,
generalizing a result in the literature for the simplest case. We also study
the U(1)_R anomaly for d=4 N=1 conformal field theories that arise from
orientifolds of the conifold. We find agreement between the field- and
string-theoretic calculations, confirming a prediction of the AdS/CFT
correspondence at order 1/N for string theories on AdS_5 x T^{11}/Z_2.
