A high performance liquid chromatographic method combined with diode array detection is described by which the valerian constituents valtrate, isovaltrate, acevaltrate, didrovaltrate, isovaleroxyhydroxydidrovaltrate, valerenic acid, hydroxyvalerenic acid and acetoxyvalerenic acid, as well as the valepotriate decomposition products baldrinal and homobaldrinal, can be separated and identified simultaneously. Using this procedure, roots of Valeriana officinalis, which are used for the production of phytomedicines, were analysed. The influence of different ethanol:water mixtures, used as extraction liquid, on the composition of extracts of V. officinalis is reported. The analytical procedure was also applied to a number of valerian-containing phytomedicines available on the Dutch market. In order to study the stability of the valepotriates and the formation of their decomposition product(s), samples of freshly prepared valerian tinctures were analysed after being stored at 4, 20, and 36°C for up to one month.