El Jem is on the main railway line between Tunis and Sfax, which makes it unusually easy to reach by train for a small Tunisian town. The journey from Tunis takes around two and a half to three hours; from Sfax it is about one hour. The station is a short walk from the amphitheatre.
By road, El Jem sits on the GP1, the main coastal highway. From Sousse the drive takes about an hour; from Sfax, about 45 minutes. Louages (shared long-distance taxis) run from Sousse and Sfax to El Jem, departing when full.
Most visitors come as a day trip from Sousse, Mahdia, or Sfax. If you want to see the amphitheatre in the late afternoon light after the tour groups leave, staying overnight is worthwhile — there are a few small hotels and guesthouses in town.