Plants from five inter-varietal crosses of the apricot cultivars Bergeron, Stark Early Orange and Stella were tested for their resistance to Crown Gall in field conditions at Velestino, Greece. One-year-old plants were inoculated by immersing the roots in a suspension of a mixture of local strains of Agrobacterium tumefaciens immediately before they were planted. Resistance was evaluated by the weight of the galls eight months after inoculation. Segregation of characters was observed in all the descents, demonstrating the heterozygotic nature of the parent cultivars. The distributions of gall weights obtained in the five hybrid families indicate that at least two allele pairs are involved in the determination of the level of resistance to the disease.