New Year's Eve, threatening transport chaos on one of the busiest nights of the year.
The RMT union said a ballot of over 4,000 underground staff had voted to strike on December 31 and January 8 following a dispute concerning staff cuts and working hours,
RMT General Secretary Bob Crow said frontline station staff, who were praised for their work on July 7 when three bombs were detonated on the Underground, were facing the sack.
The RMT has also complained about a change in working hours and job roles.
A London Underground spokesman said there would be no overall cuts in staff numbers and pointed out that the RMT had originally backed the change to a shorter, 35-hour working week.
The spokesman said the two groups were still in negotiations however and that London Underground hoped to avert the strike.