Labarthe-sur-Lèze (French pronunciation: [labaʁt syʁ lɛz], literally Labarthe on Lèze; Occitan: La Barta de Lesat) is a commune in the Haute-Garonne department in southwestern France.

The Lèze forms part of the commune's southern border, flows northward through the eastern part of the commune, then flows into the Ariège, which forms the commune's northeastern border.

Historical population

Year Pop. ±% p.a. 1793 422 —     1800 426 +0.13% 1806 428 +0.08% 1821 563 +1.84% 1831 549 −0.25% 1836 575 +0.93% 1841 547 −0.99% 1846 609 +2.17% 1851 605 −0.13% 1856 587 −0.60% 1861 584 −0.10% 1866 575 −0.31% 1872 523 −1.57% 1876 514 −0.43% 1881 531 +0.65% 1886 549 +0.67% 1891 544 −0.18% 1896 535 −0.33% 1901 515 −0.76%	Year Pop. ±% p.a. 1906 538 +0.88% 1911 509 −1.10% 1921 500 −0.18% 1926 503 +0.12% 1931 507 +0.16% 1936 477 −1.21% 1946 460 −0.36% 1954 527 +1.71% 1962 518 −0.22% 1968 810 +7.74% 1975 1,672 +10.91% 1982 2,110 +3.38% 1990 3,772 +7.53% 1999 4,632 +2.31% 2007 4,740 +0.29% 2012 5,059 +1.31% 2017 6,178 +4.08% 2018 6,275 +1.57%
Source: EHESS and INSEE (1968-2017)

Labarthe-sur-Lèze is twinned with:

• Breda di Piave, Italy

Communes of the Haute-Garonne department