Alzheimer's disease (AD) is a progressive neurodegenerative disorder that causes memory and cognitive deficits. The present study was carried out to evaluate the protective effects of fucoidan in monocrotophos induced AD in Drosophila melanogaster. In silico studies showed that fucoidan exhibited binding energy of -9.3 kcal with proteins. Consistent with this, fucoidan, in a dose and time-dependent fashion, had inhibitory activity against cholinergic and monoamine-metabolized enzymes in vitro. Fucoidan inhibited the increase in total mRNA and protein in monocrotophos fed flies and prevented changes in biochemicals, neurochemicals and latency time of locomotor, learning and memory induced by monocrotophos. Together, the findings show that fucoidan serves a neuroprotective effect in Alzheimer's disease model in D. melanogaster.