Previous studies have shown that S-adenosylmethionine synthetase-1 (SAMS-1) might be involved in the lifespan extension induced by dietary restriction (DR). In C. elegans, there are five S-adenosylmethionine synthetases, SAMS-1, SAMS-2, SAMS-3, SAMS-4, and SAMS-5. However, little is known with regard to the roles of other SAMs in the regulation of longevity. Through RNAi knockdown assays, we found that, like sams-1, inhibition of sams-5 by RNAi or genetic deletion extends the lifespan of wildtype animals. Interestingly, unlike sams-1 mutants, sams-5 mutants does not exhibit the intestinal vacuoles accumulation phenotypes, which is a indication of defected lipid synthesis. The expression pattern of sams-5 is also distinct from that of sams-1. In larvae stages, SAMS-5 is expressed in the intestine and a subset of neurons. However, the expression of SAMS-5 in the intestine is vanished in young adults. Genetic epistasis analysis suggests that sams-5 is not required for the lifespan regulation of DR, in which sams-1 plays an important role. Together, our studies suggest that sams-5 might act through a different pathway from sams-1 to modulate longevity.