GOTHENBURG, Sweden — Not far from the Sticky Fingers nightclub, three Romanian women were hunched against the cold on a street corner. When a man walked by, the women, in broken Swedish and English, tried to tempt him to buy sex.

On this dismal street in Gothenburg, Sweden’s second-largest city, the same scene plays out every Friday night. Until recently, Daniella, 34, who was brought to Sweden from Romania by a pimp 10 years ago, was a part of it.

Now, Daniella, who asked that her full name not be used, has walked away from that life. After the pimp was sent to jail for four years, she turned to a volunteer group for help finding a way off the streets and became part of a broad decline in prostitution in Sweden.

Sweden’s pioneering law criminalizing the purchase of sex while allowing its sale — putting the criminal burden on the buyer, not the prostitute, while providing more assistance to women who want to stop selling sex — has been considered a success and a model for other countries since it was introduced in 1999. A study issued Friday by a government agency in Stockholm found that street prostitution had been cut by more than half since 1995 and that the number of men admitting to having purchased sex was down more than 40 percent.