Recent evidence suggests that single dose administration of ginseng can improve certain aspects of cognitive performance and mood in healthy young volunteers in a dose and time dependent manner. The aim of this study was to investigate the effect of acute administration of 400 mg of a standardised Panax ginseng extract (G115®, Pharmaton SA) on mood and cognitive performance. Following a double-blind, placebo controlled, balanced, cross-over design, thirty healthy young adult volunteers received 400 mg of ginseng, and a matching inert placebo, in a counterbalanced order, with a 7-day washout period between treatments. Following baseline evaluation of cognitive performance and mood measures, participants' cognitive performance and mood was assessed again 90 minutes after drug ingestion. Ginseng improved speed of attention, indicating a beneficial effect on participants' ability to allocate attentional processes to a particular task. No significant effect was observed on any other aspect of cognitive performance and on self-reported mood measures. Previous research demonstrated no improvement on attentional processes, but significant improvements on tasks associated with episodic memory performance following administration of 4OO mg of ginseng when participants were tested 1h, 2.5h, 4,h and 6h post ingestion. Consequently, it may be the ease that ginseng offers alternative windows of therapeutic opportunity on different aspects of cognitive performance at different time points.