Acetylcholinesterase inhibitory activity of 10 Fumaria species (F. asepala, F. capreolata, F. cilicica, F. densiflora, F. judaica, F. kralikii, F. macrocarpa, F. parviflora, F. petteri subsp. thuretii and F. vaillantii) was measured by a modified spectrophotometric method developed by Ellman. All of the extracts displayed high inhibitory activity, ranging between 84.98±1.07 % and 96.89±0.17 %. The results were compared to galanthamine as the reference compound. Bioactivity-directed fractionation of F. vaillantii afforded a number of isoquinoline-type alkaloids as the active constituents identified by he means of spectroscopic techniques.