Samples of three SNC meteorites-Shergotty, Chassigny, and Elephant Moraine (EETA 79001)-have been analyzed for their contents and stable isotopic compositions of carbon using stepped combustion in an attempt to resolve indigenous components from terrestrial contaminants. The rarity of most of the SNC meteorites precludes the use of large samples for analysis; hence carbon isotopic compositions have been determined by static mass spectrometry. In all three cases, ca. 90% of the carbon was liberated below 500 ¿C; the isotopic composition of this material being strongly suggestive of terrestrial contamination. At higher extraction temperatures, a range in Δ13C values of -11 to -41 was found which, although not uncommon for carbon in terrestrial igneous rocks, is clearly distinct from the values postulated for the ''bulk'' Earth (Δ13C ca. -5%). The presence of several carbonaceous components was inferred from the data, although only tentative suggestions can be made on the nature of most of them. Certain similarities in the carbon isotope versus temperature profiles are observed that may indicate a common origin for the three meteorites, but the lack of isotopic data from analogous terrestrial rocks and the absence of petrographic evidence of carbonaceous material in the SNC's remains an obstacle to the complete interpretation of the present results.