Seventeen avocado selections from the U.S. Dept. of Agriculture Miami National Clonal Germplasm Repository were bioassayed for antibiosis to Caribbean fruit fly eggs and larvae. Two colony-reared strains of flies were used. Fourteen of the selections did not support any development of immature stages to the adult stage. The results support the contention that highly resistant cultivars would not pose a high risk of spreading Caribbean fruit fly to foreign markets even without postharvest disinfestation treatment.