Identifying and tracking cells in the brain is a challenging task, requiring advanced molecular biology techniques and precise anatomical information. We have applied the principle of RGB marking to the long-term marking and tracking of progenitor and mature cells in the adult brain. Briefly, multicolor RGB marking is based on the simultaneous, lentiviral vector-mediated expression of three genes encoding fluorescent proteins in the three basic colors (red, green, and blue). Here, we show the application of RGB marking to the stable multicolor marking of adult granule cells in the hippocampus. This technique provides each individual cell with a characteristic hue, which facilitates their anatomical identification and spatial tracking. Multicolor RBG marking of mature neurons can provide an effective approach to dissect the function of individual cells, as it allows combination with functional techniques, facilitating the understanding of complex neuronal populations such as that of the dentate gyrus.