A giant swastika was painted outside a house in Hendon in the middle of the night.
The family, in Shirehall Park, awoke to find the blue Nazi symbol emblazoned on the wall above their front porch on Monday morning.
The homeowners, who are Jewish, have since painted over the symbol, which was the emblem of the German Nazi party.
The Community Security Trust, a Jewish security company that monitors anti-Semitism, said: “We are aware of the graffiti and we are working with the police on all reported incidents of anti-Semitism.”
Barnet Police have now launched an investigation into the incident, which is being treated as criminal damage. No arrests have been made.