Abstract　 　 
I'll present a a carefully selected sub-sample of Swift long GRBs that is complete in redshift. This sample is free of selection effects (except flux limit) providing the possibility to investigate the rest frame physical properties of the whole class of long GRBs in an unbiased way. The high level of redshift completeness (>91%) allows us to draw few important conclusions for the class of long GRBs: 1) constrain for the first time the GRB luminosity function and its evolution; 2) derive the intrinsic absorbing X-ray column density; 3) investigate in details the properties of the sub-class of Dark Bursts; 4) perform correlation studies.