Upper House leader Tony Kelly walked out of the Legislative Council just before 1am (AEST) today, leaving 15 pieces of Government legislation unconsidered.
These included the vote on the Government's plans to privatise NSW Lotteries, which was likely to be defeated.
With no minister or parliamentary secretary present, president Peter Primrose closed down the Upper House until the "ringing of the long bell".
That long bell could ring at any time of the Government's choosing.
But it is unlikely to be heard until after the return from the winter recess on September 1, even though the Upper House was scheduled to sit today.
In protest, Liberal, Nationals, Greens and the one Independent MP arrived at the doors of the Legislative Council at 11am (AEST), only to find them locked.
It is believed to be the first time the Upper House has been shut down in such a manner since its inception in 1824.
"I've never seen a situation where a house has been shut down on a long bell for up to three months," Greens MP Ian Cohen said.
Opposition Leader in the Upper House Mike Gallacher said Mr Kelly all but ran out of the house when it appeared the Coalition would oppose moves to adjourn a day early for the winter break.
"By the time we turned around, in the blink of an eye Tony Kelly was not only gone from the house, he was gone from the Parliament," Mr Gallacher said.
"We couldn't find him, no one knew where he was.
"We're in limbo. The Parliament is effectively still sitting.
"We're just being denied access to the Parliament."
As the Upper House has not been adjourned, when Parliament does resume, Hansard will record the proceedings as having taken place on June 24.