Four mutant genes (unc-17, unc-18, unc-41 and unc-13) have been identified that result in abnormal accumulation of acetylcholine (ACh). We have now identified 3 more such genes (unc-63, unc-11 and unc-64). In addition to the abnormal accumulation of ACh, mutants in these 7 genes possess common phenotypes in locomotion, resistance to inhibitors of acetylcholinesterase (AChE) and in post-embryonic development. These results suggest that the 7 genes are involved in some related functions.