It is controversially discussed, whether ß-carboline alkaloids, like harmane or harmaline have neuroprotective effects in the nervous system. While it is known that ß-carboline alkaloids have several actions at benzodiazepine-, GABA_A- and 5-HT-receptors, we recently have demonstrated that they concentration dependently (10 - 500 mM; Splettstoesser et al., 2005) reduce currents through voltage gated calcium channels in dorsal root ganglion (DRG) neurones of rats. Since calcium is one of the most important second messengers in the cell, these results rise the question whether a reduced calcium current results in a disturbed calcium homeostasis of the cells. Therefore, we have tested the influence of harmaline on the calcium homeostasis in DRG-neurones of 21 day old Wistar rats. Calcium measurements were performed with a confocal laser imaging system (Zeiss 510) and the calcium sensitive dyes Calcium Green for cytosolic calcium and rhod-2 for calcium within the internal stores. 100 mM harmaline decreased the calcium dependent fluorescence in the cytosol by 20 % while the intensity in the nucleus and nucleolus increased about 40 %. Similar effects were observed at a concentration of 250 mM. In regard to the importance of calcium in the modulation of intracellular pathways, these modulations of the calcium homeostasis might be an other step to understand the possible neuroprotective effects of harmaline in the nervous system.