Commuters should prepare for delays, not least considering these two lines alone serve around 900,000 passengers a day.
The RATP strike comes on the same day as the latest nationwide day of action in protest against the government's planned labour reforms.
The protest means that it won't just be transport services in the capital that face disruption.
While services on the TGV line that runs from Paris to the east of France will not be affected, only three out of four TGV trains will be running on the line from the capital to the Atlantic coast and the south east.
Only 50 percent of TGV trains will be running from Paris to the north of the country.
Intercity and TER trains will also only be running around halve their usual services around the country, although the in reality the situation may be even worse in certain parts of the country like the south east.
Eurostar trains and other international services however will not be affected by the strike.
The day of action will also see high schools closed in the Paris region as students continue to protest while some Air France flights may be delayed as workers join the movement.
The disruption to flights could be more widespread however with air traffic controllers also set to join the walk-out. Aviation authorities won't know how bad the impact will be until Thursday.
Demonstrations are planed to take place across the country, including one by hospital staff in Paris, who are also in a dispute with local health authorities over changes to their work patterns.