Litchi chinensis (Sapindaceae) is a tree that originates from China and is cultivated for its sweet fruits all over the world in warm climates. Unusual fatty acids such as cyclopropanoic fatty acids have been identified in the seeds of Litchi. Because of their potential value for industry (as inks, cosmetics, detergents, lubricants, etc.), the variability in the relative levels of unusual fatty acids in the seeds of 28 different Litchi varieties was analysed at two locations (on Réunion Island in the Indian Ocean) and on two different harvest dates. Except for one variety, all the seeds contained cis-9,10-methylene-octadecanoic acid (C(19)CA) at a relative level of 35-48%. The only variety that contained no or only traces of C(19)CA was Groff, seeds of which were significantly much smaller than those from all other varieties.