In the framework of relativistic quark models, we consider the structure-dependent part of the decay ${\pi }^{+}\to e^{+}{\nu }_e\gamma$ and evaluate the ratio, $\gamma$, of the axial-vector form factor to the vector form factor. For masses of the quarks much larger than the pion mass we find $\gamma \lesssim 1$. This is different from previous predictions, made in the static quark model, which yield $\gamma =0\mathrm{}$. If the pion is treated as a nucleon-antinucleon pair, $\gamma \simeq 0.4$ in better agreement with experiments.

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