Electromagnetic mixing of isospin eigenstates for the neutral mesons leads to charge-asymmetry effects in the NN interaction. This is discussed in terms of a single-meson-exchange model in which the coupling constants are taken from SU 3 and from phenomenological estimates. Mixing of the vector mesons is considerably more important here than mixing of the pseudoscalar mesons. The difference ( a nn − a pp) between scattering lengths for the strong n-n and p-p interactions could be about −1.5 fm, when the n-p mass difference (which contributes about −0.5 fm) is also considered. Other charge-asymmetry effects which have been estimated are much smaller.