 We hypothesize that Panax Ginseng , with multiple interactions with chemical pathways in the brain described as neurotransmitter systems Dopamine, GABA and NMDA can improve the residual symptoms of schizophrenia when added to the antipsychotics currently used in the treatment of schizophrenia. Furthermore, in view of previous studies of Ginseng in enhancing memory , we hypothesize that the standardized formulation of Ginseng Ginsana-115 from Boehringer Ingelheim-Pharmaton,Switzerland will optimize the antipsychotics in cognition impairment and negative symptoms. In the 18-week RCT cross-over study, schizophrenic subjects will be treated with either Ginsana-115 100 mg or 200 mg by oral route or placebo in a cross-over design. we plan to recruit 60 subjects diagnosed as schizophrenia from the four sites : London-St. Thomas, Ontario, Canada; Kingston Ontario Canada; Thunderbay, Ontario Canada and Middlesex, United Kingdom. 