The ethanolic extract from the leaves of Ocimum sanctum Linn was screened for its effects on the noise induced changes in the central cholinergic system of albino rats by investigating the acetylcholine content and acetylcholinesterase activity in discrete areas of brain. Exposure to noise (10 kHz:100 dB) stress for 30 min caused a significant reduction in total acetylcholine content and increase in the activity of acetylcholinesterase in cerebral cortex, corpus striatum, hypothalamus and hippocampus of brain. Pretreatment of the animals with ethanol extract of Ocimum sanctum leaves for 7 days prevented the noise induced changes in these two cholinergic parameters in all the four areas of brain. The results of the study indicate the protective nature of the plant material on the brain tissues against the detrimental effect of noise stress.