An isocratic HPLC system is described which allows the separation of the iridoid and indole precursors of terpenoid indole alkaloids, which are present in a single crude extract. The system consists of a column of LiChrospher 60 RP select B 5 µm, 250 × 4 mm (Merck) with an eluent of 1% formic acid-acetonitrile-trichloroacetic acid (100:10:0.25, v:v:w) at a flow of 1.2 ml/min. In the suspension cultures of Catharanthus roseus secologanin and tryptophan were detected. In the cultures of Tabernaemontana divaricata loganin, tryptophan, and tryptamine accumulated.