Women who wear face-covering Islamic veils in public in France are now breaking the law.
Veiled women risk a €150 fine, a police record and being sent to special citizenship classes.
People who force women to wear a veil are subject to a much larger fine.
The ban was approved by parliament in September and came into effect on Monday.
It affects women who wear the niqab, which has just a slit for the eyes, and the burka, which has a mesh screen over the eyes.
Both are quite rare in France, whose at least five million Muslims are largely moderate.
President Nicolas Sarkozy has said the veils imprison women and are an affront to principles of equality and secularism.