  We analyse the level of nuclear activity in galaxies belonging to UZC-CGs.
Spectra are available for 868 galaxies (90% of the whole catalog); 67 % of them
show nuclear activity (AGN or Star formation). To carry out a detailed study
about the nuclear activity and its relationship with properties of the host
galaxy and parent group we select a sample of 215 groups with spectra available
for all their members. From the analysis of this sample and using diagnostic
diagrams to do the nuclear classification we found that 37% of emission
galaxies host an HII nuclear region, 43% an AGN and 20% a Transition Object.
AGNs are located mainly in bright early type galaxies meanwhile HII are in
fainter and later types. Groups dominated by HII show significant lower
velocity dispersions and larger sizes than groups dominated by AGNs or TO.
