  We present a study of the stellar populations and gas physical conditions in
Circumnuclear Star Forming Regions (CNSFR) based on broad and narrow band
photometry and spectrophotometric data, which have been analyzed with the use
of evolutionary population synthesis and photoionization models. It is found
that most CNSFR show composite stellar populations of slightly different ages.
They seem to have the highest abundances in HII region-like objects, showing
also N/O overabundances and S/O underabundances by a factor of about three.
Also, CNSFR as a class, segregate from the disk HII region family, clustering
around smaller $\eta$' values, and thereforefore higher ionizing temperatures.
