Acetylcholine (ACh) and nicotinic acetylcholine receptors (nAChR) play important roles in the transmission of electrical signals in the brain. The diversity of nAChR subunits contributes to differential regulation of signal transmission at synapses. Twenty types of nAChR subunits were previously identified in two gastropod molluscs, Aplysia californica and Lymnaea stagnalis (van Nierop et al., 2006; White et al., 2014). Here, they were identified in six nudipleura molluscs: Flabellina iodinea, Hermissenda crassicornis, Tritonia diomedea, Pleurobranchaea californica, Melibe leonina and Dendronotus iris. In addition, four novel nAChR subunits were predicted with an ortholog-based approach. Bioinformatically determined gene expression levels showed species differences. Whole-mount in situ hybridization using choline acetyltransferase gene probes localized cholinergic neurons in the brains of Dendronotus and Melibe. Investigation and comparison of nAChRs and cholinergic neurons in the brains of these animals will help to understand how neurochemistry relates to the organization and evolution of neural circuitry.