The CRISPR RNA-guided Cas9 nuclease has been adapted for precise genome engineering in Drosophila, enabling efficient germline transmission of genomic modifications. This system allows for targeted gene editing through the creation of double-strand breaks (DSBs) that are repaired by homologous recombination (HR) or nonhomologous end joining (NHEJ). The CRISPR system uses a single RNA guide to direct Cas9 to specific DNA sequences, offering a simpler and more efficient alternative to zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), which require unique proteins for each genomic manipulation. In Drosophila, the CRISPR system was successfully used to induce site-specific DSBs in genes such as yellow and rosy, leading to targeted deletions and replacements. The system was also shown to generate precise genome modifications that are transmitted through the germline, resulting in stable mutant strains. The efficiency of the CRISPR system was demonstrated through the generation of targeted deletions and replacements, including the replacement of the yellow gene with an attP docking site. The system was also shown to be effective in generating mosaic individuals and transmitting mutations to offspring. The CRISPR system was found to be highly specific, with minimal off-target effects, and was able to generate mutations with high efficiency. The system was also shown to be effective in generating large defined deletions through multiplex targeting. The ability to generate precise genome modifications in Drosophila opens the door to rapid engineering of the genome to investigate gene function and regulation. The CRISPR system offers a powerful tool for genome editing in Drosophila, with the potential for further optimization and application in other organisms.The CRISPR RNA-guided Cas9 nuclease has been adapted for precise genome engineering in Drosophila, enabling efficient germline transmission of genomic modifications. This system allows for targeted gene editing through the creation of double-strand breaks (DSBs) that are repaired by homologous recombination (HR) or nonhomologous end joining (NHEJ). The CRISPR system uses a single RNA guide to direct Cas9 to specific DNA sequences, offering a simpler and more efficient alternative to zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), which require unique proteins for each genomic manipulation. In Drosophila, the CRISPR system was successfully used to induce site-specific DSBs in genes such as yellow and rosy, leading to targeted deletions and replacements. The system was also shown to generate precise genome modifications that are transmitted through the germline, resulting in stable mutant strains. The efficiency of the CRISPR system was demonstrated through the generation of targeted deletions and replacements, including the replacement of the yellow gene with an attP docking site. The system was also shown to be effective in generating mosaic individuals and transmitting mutations to offspring. The CRISPR system was found to be highly specific, with minimal off-target effects, and was able to generate mutations with high efficiency. The system was also shown to be effective in generating large defined deletions through multiplex targeting. The ability to generate precise genome modifications in Drosophila opens the door to rapid engineering of the genome to investigate gene function and regulation. The CRISPR system offers a powerful tool for genome editing in Drosophila, with the potential for further optimization and application in other organisms.