The branching ratio of the τ lepton to a neutral kaon meson is measured from a sample of approximately 200,000 τ decays recorded by the OPAL detector at centre-ofmass energies near the Z 0 resonance. The measurement is based on two samples which identify one-prong τ decays with K 0 L and K 0 S mesons. The combined branching ratios are measured to bewhere the first error is statistical and the second systematic.