Abstract
Organic compounds exhibit SHG efficiency which has order of magnitude largerthan widely known inorganic materials. They also offer the flexibility of molecular design and the promise of virtually an unlimited number of crystalline structures. Due to delocalization character, tailor made organic crystals can be grown which posse’s far superior properties than that of inorganic material; hence researchers focus their attention on the exploration of newer and newer organic NLO crystals. In this paper deals with the organic NLO crystals introduction, literature and currents trends.