AbstractAxonal fusion is a neuronal repair mechanism that results in the reconnection of severed axon fragments, leading to the restoration of cytoplasmic continuity and neuronal function. While synaptic vesicle recycling has been linked to axonal regeneration, its role in axonal fusion remains unknown. Dynamin proteins are large GTPases that hydrolyze lipid-binding membranes to carry out clathrin-mediated synaptic vesicle recycling. Here, we show that theCaenorhabditis elegansdynamin protein DYN-1 is a key component of the axonal fusion machinery. Animals carrying a temperature-sensitive allele ofdyn-1(ky51)displayed wild-type levels of axonal fusion at the permissive temperature (15°C) but presented strongly reduced levels at the restrictive temperature (25°C). Furthermore, the average length of regrowth was significantly diminished indyn-1(ky51)animals at the restrictive temperature. The expression of wild-type DYN-1 cell-autonomously intodyn-1(ky51)mutant animals rescued both the axonal fusion and regrowth defects. Furthermore, DYN-1 was not required prior to axonal injury, suggesting that it functions specifically after injury to control axonal fusion. Finally, using epistatic analyses and superresolution imaging, we demonstrate that DYN-1 regulates the levels of the fusogen protein EFF-1 post-injury to mediate axonal fusion. Together, these results establish DYN-1 as a novel regulator of axonal fusion.