The R4 is a line of Rodalies de Catalunya's Barcelona commuter rail service, operated by Renfe Operadora.

It runs northwards from the northern limits of the province of Tarragona to Barcelona, passing through the inland Alt Penedès region.

[5] In the long-term future, it is projected that the route of the R4 south of Barcelona will be transferred to the R2, and all its services will terminate at Barcelona–El Prat Airport.

[6] The following table lists the name of each station served by line R4 in order from south to north; the station's service pattern offered by R4 trains; the transfers to other Rodalies de Catalunya lines, including both commuter and regional rail services; remarkable transfers to other transport systems; the municipality in which each station is located; and the fare zone each station belongs to according to the Autoritat del Transport Metropolità (ATM Àrea de Barcelona) fare-integrated public transport system and Rodalies de Catalunya's own fare zone system for Barcelona commuter rail service lines.

[9][10] Another derailment occurred on 8 February 2019 between Sant Vicenç de Castellet and Manresa, killing the driver and injuring several other people.