Both infusion and decoction of the four tea varieties were assayed for acetylcholinesterase (AChE) inhibitory property. Theaflavin and thearubigin, the two most exclusive polyphenols of black tea, were also studied for their AChE properties. The present study showed that infusion and decoction of each variety of tea inhibited AChE in a dose dependent manner. There was no significant difference in activity between the varieties. In general the activity of tea decoction was significantly higher than that of the infusion. Theaflavin and thearubigin also showed AChE inhibitory properties in a dose dependent manner. The individual tea extract had higher activity than either theaflavin or thearubigin. The present study suggests that AChE inhibitory activity of black tea could be due to theaflavin, thearubigin and other tea flavonols, phenols or some other constituents and perhaps a combination of some of the constituents acting synergistically.