  Determining the metal content of low-mass members of young associations
provides a tool that addresses different issues, such as triggered star
formation or the link between the metal-rich nature of planet-host stars and
the early phases of planet formation. The Orion complex is a well known example
of possible triggered star formation and is known to host a rich variety of
proto-planetary disks around its low-mass stars. Available metallicity
measurements yield discrepant results. We analyzed FLAMES/UVES and Giraffe
spectra of low-mass members of three groups/clusters belonging to the Orion
association. Our goal is the homogeneous determination of the metallicity of
the sample stars, which allows us to look for [Fe/H] differences between the
three regions and for the possible presence of metal-rich stars. Nine members
of the ONC and one star each in the $\lambda$ Ori cluster and OB1b subgroup
were analyzed. After the veiling determination, we retrieved the metallicity by
means of equivalent widths and/or spectral synthesis using MOOG. We obtain an
average metallicity for the ONC [Fe/H]=-0.01\pm 0.04. No metal-rich stars were
detected and the dispersion within our sample is consistent with measurement
uncertainties. The metallicity of the $\lambda$ Ori member is also solar, while
the OB1b star has an [Fe/H] significantly below the ONC average. If confirmed
by additional [Fe/H] determinations in the OB1b subgroup, this result would
support the triggered star formation and the self-enrichment scenario for the
Orion complex.
