The premetro and tram route 4 in Brussels, Belgium, is operated by STIB/MIVB, and connects the Stalle Parking stop in the southern municipality of Uccle to Brussels-North railway station in the municipality of Schaerbeek. It was created on 2 July 2007 as a new route between Esplanade and Stalle Parking. On 31 August 2009, the route was shortened with a new terminus at Brussels-North, while line 3 was expanded between Brussels-North and Esplanade. The colour of the signage for this line is pink.
Following the disbandment of line 3 in 2024, only tram lines 4 and 10 remain in the North–South Axis that runs underneath the Pentagon (Brussels' city centre). Both lines 4 and 10 have a 6-minute schedule during rush hour and are serviced by the modern low-floor trams (Bombardier T3000 and T4000).