Transilien Line N is a railway line of the Paris Transilien suburban rail network operated by the SNCF. The trains on this line travel between Gare Montparnasse in Paris and the west of Île-de-France region, with termini in Rambouillet, Dreux and Mantes-la-Jolie on a total of 117 km (75 mi). The line has a total of 117,000 passengers per weekday. Passenger service started in 2004.

Transilien is the brand name given to the commuter rail network serving Île-de-France, the region surrounding and including the city of Paris. The network consists of nine lines: H, J, K, L, N, P, R, U, and V each operated by SNCF, the state-owned French railway company. The lines begin and end in major Parisian stations, except for lines U and V which connect major stations outside the Paris city borders. Unlike the RER network, the Transilien trains do not cross through the Paris city centre.