In 1994, CIRAD-FLHOR started a programme of somatic hybridisation in citrus targeting the creation of new rootstocks and the diversification of the tetraploid genitor pool for triploid cultivar breeding. Protoplast electrofusion has been used to create new interspecific and intergeneric somatic hybrids. Heterofusion rates were evaluated after protoplast fusion by using flow cytometry. Ploidy level evaluation with this technique, in association with molecular marker analysis, has allowed a study of the origin of nuclear and cytoplasmic genomes of the regenerated plants and calli. Even though heterofusion rates were quite low (between 2.7% and 4.8%), tetraploid somatic hybrids were obtained from both 'nucellar callus protoplast + leaf protoplast'and 'callus protoplast + callus protoplast' combinations. However, plant recovery, was easier from the callus + leaf protoplast combination. The production of two intergeneric tetraploid somatic hybrids (C. deliciosa + Fortunella japonica, C. deliciosa + Poncirus trifoliata), five interspecific tetraploid somatic hybrids (C. deliciosa + C. sinensis, C. deliciosa + C. aurantifolia, C. deliciosa + C. limon, C. paradisi + C. aurantifolia, C. deliciosa + C. Sinensis) and one alloplasmic diploid (C. limon nuclear genome + C. deliciosa mitochondrial genome) are described.