To the best of our knowledge, this is the first report on the association of 5HTTLPR, STin2, TPH1 (A218T), and TPH2 (G703T) polymorphisms in opioid dependence in the Indian population, in which the SLC6A4 5HTTLPR and STin2 VNTR have shown an association with opioid dependence and aggressiveness respectively among the patients. This evidence concerns the gene SLC6A4 and opiate dependence.