Many studies have suggested the possibility of substantial ethnic differences in responses to psychotropic agents. These differences could be caused by pharmacokinetic. Pharmacodynamic. And psychological factors. While some of these differences are clearly determined by genetic factors. Others appear to be linked to dietary practices or to other culturally related behavioral faotors. ln this paper. The authors reviewed pharmacokinetic, pharmacodynamic and cultural psychological factors, ali of which could be responsible for such ethnic variations.