increasing crop genetic diversity has the potential to enhance pollination services, by contributing to the long-term stability of agroecosystems. different species of the genus citrus, including grapefruit, are cultivated worldwide. in argentina, 30% of the total national yield is concentrated in the northwestern part of the country where new cultivars have arisen. we analyzed genetic variation and diversity within and among four plantations of citrus paradisi for 11 isozyme loci. although representing single cultivars clonally propagated, within plantations genetic variation was high. observed heterozygosity ranged from 33 to 36.5%. the number of alleles per locus ranged from 2.4 to 2.6, and polymorphism from 72.7 to 81.8% and for the species in the area reaches 100%. most of the variation was found within (90%) rather than between plantations. also, divergence among plantations was only 12%. despite self-compatibility, fruit production in these plantations benefits from cross-pollination. therefore, our results highlight the importance of preserving high levels of genetic variation to increase sustainability and productivity of agricultural systems.