The aim of this study was to explore the acetylcholinesterase (AChE) inhibition of several Icelandic medicinal herbs. Ethanolic extracts of Angelica archangelica seeds and the aerial parts of Geranium sylvaticum proved effective, with IC50 values of 2.20 mg/ml and 3.56 mg/ml, respectively. The activity of imperatorin and xanthotoxin from A. archangelica was measured. Xanthotoxin proved much more potent than imperatorin, with an IC50 value of 155 microg/ml (0.72 mM) but that for imperatorin was above 274 microg/ml (1.01 mM). However, furanocoumarins seem to have a minor part in the total activity of this extract. Synergistic interaction was observed between the extracts of A. archangelica and G. sylvaticum. Several medicinal herbs (Achillea millefolium, Filipendula ulmaria, Thymus praecox and Matricaria maritima) did not show AChE inhibitory activity.