Rim is an active zone protein which is suggested to be involved in the regulation of vesicle exocytosis and synaptic plasticity. The C. elegans genome encodes only one Rim gene, unc-10. In this study, we demonstrate that UNC-10 is involved in the dense core vesicle (DCV) exocytosis in C. elegans neurons. We find that unc-10 mutants exhibit reduced peptide release in vivo. In IDA-1::GFP labelled ALA neurons, which serve as a good model for studying DCV exocytosis, mutations of UNC-10 lead to a visible reduction of the readily released pool (RRP) size. The analysis of vesicular docking by total internal reflection fluorescence microscopy (TIRFM) reveals that the loss of function of unc-10 hinders the docking of DCVs in neurons. The above results provide evidence that UNC-10 is required for the exocytosis of DCVs and may be involved in the docking step of DCV release.