His most acclaimed is a 1968 short, The Perfect Human, which also featured in the 2003 film The Five Obstructions made by Leth and Lars von Trier.

Leth's sports documentaries bring an epic, almost mythic, dimension to the field, as seen in Stars and Watercarriers (Stjernerne og Vandbærerne) (1973) and A Sunday in Hell (En forårsdag i helvede) (1977).

He has also been a professor at the Danish National Film School in Copenhagen, at the State Studiocenter in Oslo and has lectured at UCLA, Berkeley, Harvard and other American universities.

[3] He attracted controversy in Denmark after publication of his autobiography Det uperfekte menneske (The Imperfect Human).

[8][9][10] Leth has been married three times and has four children: Asger (film director),[11] Karoline, Kristian and Tomas.