  In a sample of 476931 NELGs obtained from the SDSS DR5 data we find that in
22% of the galaxies the emission line [OIII]$\lambda$5007, H$\beta$, or both,
are missing. The nature of the activity in these galaxies was determined using
a diagnostic diagram comparing the equivalent width of [NII]$\lambda$6584 with
the ratio [NII]$\lambda$6584/H$\alpha$. The majority of these galaxies are AGN.
The H$\alpha$ emission lines have a mean FWHM of 400 km s$^{-1}$ and mean
luminosity of 5.6$\times$10$^{39}$ erg s$^{-1}$, which justify their
classification as LLAGN. A study of their star formation histories using
STARLIGHT reveals no trace of star formation over the last Gyr period. The
hosts of the LLAGNs are early-type, T$\le 2$, with bulges more massive than
those of the luminous AGNs.
