Technical Abstract: The cholinergic theory of aging states that dysfunction of cholinergic neurons arising from the basal forebrain and terminating in the cortex and hippocampus may be involved in the cognitive decline that occurs during aging and Alzheimer’s disease. Despite years of research, pharmacological interventions to treat or forestall the development of Alzheimer’s disease have primarily focused on enhancing cholinergic transmission, either through increasing acetylcholine (ACh) synthesis or inhibition of the acetylcholinesterase (AChE) enzyme responsible for ACh hydrolysis. Numerous studies have demonstrated that, along with medication, lifestyle changes can positively impact cognition during aging. Specifically, dietary alterations have proven effective in reversing age-related cognitive decline in animal studies. The purpose of the present review is to review the relevant research suggesting that cholinergic functioning may be maintained via a diet containing polyunsaturated fatty acids (PUFAs). The predominant sources of polyunsaturated fatty acids in the diet are vegetable oils, nuts, and fish. The data reviewed herein indicate that, at least in animal studies, inclusion of PUFAs in the diet can improve cholinergic transmission in the brain, possibly leading to improvements in cognitive functioning.