In this study 10 guaianolide-type sesquiterpene γ-lactones named amphoricarpolides, isolated from the aerial parts of two endemic subspecies of Amphoricarpos neumayeri (ssp. neumayeri and ssp. murbeckii Bošnjak), were investigated by means of reversed-phase thin-layer chromatography. Methanol–water and tetrahydrofuran–water binary mixtures were used as mobile phase in order to determine lipophilicity parameters R and C0. Some of the investigated compounds were screened for their cytotoxic activity against HeLa and B16 cells. Chromatographically obtained lipophilicity parameters were correlated with calculated logP values and IC50 values. Principal component analysis identified the dominant pattern in the chromatographically obtained data. Copyright © 2008 John Wiley & Sons, Ltd.