Given some of the drawbacks of conventional fruit breeding, biotechnology is a workable approach to obtain improved apricot (Prunus armeniaca L.) genotypes adapted to the current climate change scenario. Moreover, regeneration of transformed apricot plants may be used for functional genomics studies. In this chapter, we describe a protocol for Agrobacterium-mediated stable transformation of hypocotyl slices from mature seeds of the apricot cultivars “Canino” and “Moniqui” and the regeneration of transformed plants. The application of a gradual increasing selection strategy based on aminoglycoside antibiotics or an inhibitory concentration of herbicide strategy during the first regeneration steps followed by a reduced concentration in the micropropagation medium allows the regeneration of transgenic apricot lines from hypocotyl slices of “Canino” and “Moniqui” cultivars with efficiencies ranging between 1.5% and 3.8%, respectively.