We present new measurements of the metallicity of 131 RR Lyrae stars in the globular cluster {omega} Centauri, using the hk index of the Caby photometric system. The hk method has distinct advantages over {delta}S and other techniques in determining the metallicity of RR Lyrae stars and has allowed us to obtain the most complete and homogeneous metallicity data to date for the RR Lyrae stars in this cluster. For RR Lyrae stars in common with the {delta}S observations of Butler, Dickens, & Epps (1978ApJ...225..148B) and Gratton, Tornambe, & Ortolani (1986A&A...169..111G), we have found that our metallicities, [Fe/H]_hk_, deviate systematically from their {delta}S metallicity, while our [Fe/H]_hk_ for well-observed, field RR_ab_ stars are consistent with previous spectroscopic measurements.