  An enigmatic, small class of IR and X-ray luminous sources, named
``Composite'' starburst/Seyfert galaxies, has been defined from IRAS and RASS
data. The objects have optical spectra dominated by the features of HII
galaxies (plus, in some cases, weak Seyfert signatures) but X-ray luminosities
higher than expected from starbursts and more typical of Seyfert nuclei. The
true nature of this class of objects is still unknown. We present Chandra data
of four of these galaxies that were obtained to investigate the nature of the
X-ray source. The X-ray spectrum, the lack of any significant extended
component, and the observed variability indicate that the AGN is the dominant
component in the X-ray domain.
