Huitlacoche galls were produced in 15 creole maize genotypes harvested at two stages of development, 23 and 28 days after inoculation, and in a hybrid genotype harvested at six stages of development. Raw and cooked galls were evaluated for proximate constituents, carbohydrate composition and antimutagenic activity. Huitlacoche grown in creole maize exhibited differences in concentrations of some of the proximate and carbohydrate components, due to genotype and stage of development; some effects were also observed in hybrid maize, as a result of stage of development and cooking. Huitlacoche has a considerable amount of crude protein (9.8% average in creole maizes, and 11.3% in hybrid maize). Most of the values for total dietary fibre, β-glucans, and total free sugars were higher than those reported for other edible mushrooms. The high concentration of antimutagenic substances appears to be an asset of this culinary delicacy.