We study orbital and physical properties of Trojan asteroids of Jupiter .
We try to discern all families previously discussed in literature , but we conclude there is only one significant family among Trojans , namely the cluster around asteroid ( 3548 ) Eurybates .
It is the only cluster , which has all of the following characteristics : ( i ) it is clearly concentrated in the proper-element space ; ( ii ) size-frequency distribution is different from background asteroids ; ( iii ) we have a reasonable collisional/dynamical model of the family .
Henceforth , we can consider it as a real collisional family .

We also report a discovery of a possible family around the asteroid ( 4709 ) Ennomos , composed mostly of small asteroids .
The asteroid ( 4709 ) Ennomos is known to have a very high albedo p _ { V } \simeq 0.15 , which may be related to a hypothetical cratering event which exposed ice ( Fernández et al .
2003 ) .
The relation between the collisional family and the exposed surface of the parent body is a unique opportunity to study the physics of cratering events .
However , more data are needed to confirm the existence of this family and its relationship with Ennomos .