A sensitive reversed-phase high-performance liquid chromatographic (HPLC) procedure for the analysis of the main parasympatholytic tropane alkaloids in plant material is described. It uses an acidic aqueous acetonitrile mobile phase and UV detection at 204 nm. It allows a good simultaneous separation of l-hyoscyamine, l-scopolamine and tropic acid, their acidic precursor. The detection limits are 20 ng for the alkaloids and 5 ng for tropic acid. A simple and rapid method, very convenient for HPLC analysis, is also described for the preparation of purified alkaloid extracts. The procedure was applied to the evaluation of the alkaloid content of Datura leaves. The results are in good correlation with those obtained with a tropic acid derivatives- specific enzyme immunoassay. © 1993.