The Ultra-Lightweight TT was a motorcycle road race that took place during the Isle of Man TT festival, an annual event at the end of May and beginning of June. Between 1951 and 1974 this race was part of the Grand Prix motorcycle racing season at world-level, representing the British round. The Ultra-Lightweight TT and the Lightweight TT races were both dropped from the 2005 Isle of Man TT race calendar due to lack of entries, but were later reinstated to the 2008 and 2009 TT race schedules held on the 4.25 mi (6.84 km) Billown Circuit.