Bruno Wiel, now 33, was left unconscious at the scene in 2006 and has no memory of the incident.
It is claimed that the four men, who are all in their twenties, began conversation with Wiel as he exited in a gay bar in Les Halles, a district of the French capital.
He entered their car and was driven to a park in Vitry-sur-Seine, where he was beaten, burned and forcibly sodomised with a stick. Wiel was left at the scene and discovered the following day.
An anonymous call following a police appeal for witnesses led to the arrest of the four defendants.
The trial, which is attracting national attention in France, could lead to life sentences for the men.
The group SOS Homophobie reported 88 cases of homophobic aggression in 2010. They deny homophobic intent. The group’s president, Bartholomé Girard, said yesterday that many victims do not want to endure a trial “because it is hard to confront their attackers”.
A verdict is expected on 28 January.