A spokesman for the League of American Theatres and Producers told AFP that the talks were still going on at 6:00pm (local time) on Sunday.
The spokesman did not disclose whether the two sides had made progress in their negotiations.
Stagehands walked out some two weeks ago, turning the lights out at some 27 Broadway theatres and leaving disappointed ticket holders arriving at theatres to find doors closed and picket lines set up outside.
Since then just one show has reopened.
Last week a judge ordered the theatre showing Dr Seuss' How the Grinch Stole Christmas! to reopen because only the theatre's landlord and not the show's producers were involved in the dispute.
The strike hinges on contract negotiations, with producers saying they are forced to hire an unnecessarily large number of stagehands, often to perform minor duties.
The unions have accused the theatres of trying to make cutbacks.
The two sides held talks last weekend, but negotiations broke down when the union representing stagehands rejected compromise proposals put forward by the producers.
The industrial action is the third stoppage on Broadway in 30 years.
The last, a strike by musicians in 2003, lasted just four days.
It is estimated to have cost theatre producers several million dollars.
This year's strike is thought to have been especially damaging since it closed down some of Broadway's most profitable shows over the lucrative Thanksgiving Day weekend. © 2007 Australian Broadcasting Corporation