  We present follow-up spectroscopy to the Calar Alto Deep Imaging Survey
(CADIS), reporting on the quasars in the CADIS 16h-field, and including
preliminary data from two other fields. In this 10' x 10' field we found six
quasars at redshift z>2.2 which are brighter than R=22 mag, while surface
densities determined in previous surveys are reported to be below one on
average. This is the highest reported surface density of high-redshift quasars
within the given limits. We believe this result to be a consequence of the
multicolor database and the search technique used in CADIS.
  Our observations further seem to indicate that the density of high-redshift
quasars is also higher than predicted by the luminosity function of Warren
(1994) by a factor of three, implying that common search methods have
overlooked the majority of high-redshift quasars at this magnitude level. In
particular, an application of the V/V max test to our preliminary list of AGNs
with R<22 mag and z<4 yields <V/V max> = 0.51 +-0.06, characterizing our
preliminary redshift distribution as flat.
