Twenty-three Amaryllidaceae alkaloids having several different ring types were evaluated for their acetylcholinesterase enzyme (AChE) inhibitory activity. The alkaloid 1-O-acetyllycorine (IC50:0.96 +/- 0.04) showed significant AChE inhibitory activity. In addition, crinine (IC50:461 +/- 14), crinamidine (IC50:300 +/- 27), epivittatine (IC50: 239 +/- 9), 6-hydroxycrinamine (IC50:490 +/- 7), N-desmethyl-8alpha-ethoxypretazettine (IC50:234 +/- 13) N-desmethyl-80-ethoxypretazettine (IC50:419 +/- 8), lycorine (IC50:213 +/- 1), and 1,2-di-O-acetyllycorine (IC50:211 +/- 10) had weak activity. Lycorine-type alkaloids were the most active alkaloids with 1-O-acetyllycorine exhibiting inhibitory effects two-fold more potent than that of galanthamine.