Start Treaty may refer to:

• START I, a bilateral treaty between the United States of America and the Union of Soviet Socialist Republics (USSR) signed on 31 July 1991
• New START, a bilateral treaty between the United States and the Russian Federation signed on April 8th, 2010

START (Strategic Arms Reduction Treaty) was a bilateral treaty between the United States of America and the Union of Soviet Socialist Republics (USSR) on the reduction and limitation of strategic offensive arms. The treaty was signed on 31 July 1991 and entered into force on 5 December 1994. The treaty barred its signatories from deploying more than 6,000 nuclear warheads atop a total of 1,600 inter-continental ballistic missiles (ICBMs) and bombers. START negotiated the largest and most complex arms control treaty in history, and its final implementation in late 2001 resulted in the removal of about 80 percent of all strategic nuclear weapons then in existence. Proposed by United States President Ronald Reagan, it was renamed START I after negotiations began on the second START treaty.