Four members of the Ukranian women's movement Femen stood wrapped in cellophane with labels attached reading "5.99 dollars, made in Ukraine."
Surrounded by passers-by and photographers, they blocked the road in the Sihlquai area where prostitutes often operate, shouting "Women aren't merchandise."
The protesters disrupted traffic for about a quarter of an hour, at one point climbing onto a Mercedes as the car's stunned driver looked on.
"We are trying to shock people to show them the reality," said one of the protesters.
"We aren't against prostitutes, but the pimps who use them."
The women arrived in Switzerland at the end of October for a tour of Europe which has included a stop outside the Paris home of former International Monetary Fund chief Dominique Strauss-Kahn.
Femen has around 300 members in Kiev and is seeking to boost its profile abroad.
The group said on Thursday it had ended its stint in Europe but promised to return "in a few months."