Bonn, the former West German capital, has introduced a "parking" meter for prostitutes, a first in Germany, in order to tax those who just work the streets, a city spokeswoman said.
"We expect to get some 200,000 euros per year from the meter," Isabelle Klotz said.
The meter, which looks like one used by drivers for parking their cars, was inaugurated at the weekend in an industrial area, near the centre of town, used by prostitutes to solicit clients.
Prostitutes have to pay six euros per night worked, regardless of how many customers they have.
On Monday when the meter was first emptied, 264 euros had been paid in, Ms Klotz said.
About 200 women are believed to work the streets in Bonn occasionally, but the average overnight tally is 20. Valid between 8pm and 6am.