Trinny & Susannah Undress the Nation is a British reality fashion-themed television documentary series on ITV featuring fashion advisors Trinny Woodall and Susannah Constantine.

The newly formatted series, stemming from Trinny & Susannah Undress..., began to air on ITV on 7 November 2007, and explores some of the major fashion problems in Britain. Numerous eye-catching stunts were filmed for the first series of the show in order to emphasise the points raised by Trinny and Susannah. One stunt included Susannah Constantine being transformed into a 70-year-old to look at how people dress for their age. Breasts, bras and uniforms were also some of the themes investigated during the first series.