The carbon isotope geochemistry of glasses from Loihi Seamount has been compared with that of MORB glasses. Stepped heating shows two carbon components in both sample suites: (1) isotopically light carbon (avg. δ¹³C = −26.3‰) released < 600°C, ascribed to surficial contamination, and (2) isotopically heavy carbon released > 600°C, regarded as indigenous. The high-temperature component in MORB samples varied from 52 to 169 ppm C, averageδ¹³C = −6.6‰, consistent with previous studies (overall MORD averageδ¹³C = −6.4 ± 0.9‰), and new results for Indian Ocean glasses are similar to Atlantic and Pacific Ocean samples. Carbon release profiles produced by stepped heating may be typical of locality, but there are no significant differences inδ¹³C values between MORB samples from different areas. Lower yields (17–110 ppm C) correlated with depth in the Loihi samples suggest that they are partially degassed. This degassing has not affectedδ¹³C values significantly (avg. −5.8‰). Loihi tholeiites have higherδ¹³C (avg. −5.6‰) than the alkali basalts (avg. −7.1‰). Carbon abundances correlate well with He concentration data. Comparison of theδ¹³C values with trace element and He, Sr, Nd, and Pb isotope data from the literature suggests that the Loihi samples with highestδ¹³C have high³He/⁴He and possibly the least depleted¹⁴³Nd/¹⁴⁴Nd and⁸⁷Sr/⁸⁶Sr. The carbon isotope data are consistent with previous models for Loihi involving several mantle sources, lithospheric contamination, and mixing. The slightly higherδ¹³C of Loihi tholeiites suggests that the undegassed “plume” component manifested by high³He/⁴He values might haveδ¹³C about 1‰ higher than the MORB average.