We investigated the relationship between the loss of nicotinic acetylcholine receptors (nAChR) and the cognitive decline or neuropathological changes seen in Alzheimer's Disease (AD) and dementia with Lewy bodies (DLB). Midfrontal (MF) cortex of 31 AD, 24 DLB and 11 non-demented controls was examined. Total plaque (TP), neuritic plaque (NP) and neurofibrillary tangle (NFT) counts were obtained. NAChR binding was assayed using 3H-epibatidine [3H-EPI]. Last Blessed Information-Memory-Concentration scores (BIMC), Mini-Mental State Examination (MMSE), Mattis Dementia Rating Scale (DRS) scores were collected. There were no correlations between 3H-EPI binding and TP, NP, NFTs counts in either AD or DLB. Last BIMC, MMSE, DRS scores did not correlate with 3H-EPI binding in AD or DLB. Thus, decline in cognitive function does not correlate with loss of nAChR in DLB or AD at the end of life suggesting that later in these diseases, loss of nAChR binding is not a reliable marker of cognitive function in AD or DLB. Loss of nAChR activity does not appear to be related to plaques or NFTs in AD or DLB.