A Dissertation Submitted in Partial Fulfillment of the Requirements for Award of the degree of Master (LLM) of Mzumbe University.Counterfeit drugs have been a problem that has for years now been a leading problem in developed and developing countries. It is now at the point that universal abolition appears to be unachievable and a challenge not only to the world but also in Tanzania. The laws and their regulatory mechanisms entrusted are examined and the researcher critically assesses them to see if they are effective to combat counterfeit drugs. For this purpose the researcher has selected Dar es salaam as a case study for easy accessibility of information. Interviews were conducted and questionnaires were distributed to the public, the authorities responsible and drug/medicine dealers. The researcher findings are then related to the overall effectiveness of the law and their regulatory mechanisms by studying their strengths and weaknesses in combating counterfeit drugs. The findings indicated that the law and their regulatory mechanisms are not effective in combating counterfeit drugs thus explains the growing business of counterfeit drugs in the country. The question of how the law and their regulatory mechanisms can be more effective in future is considered. And the researcher recommends that the laws needs reviews and more amendment and in regulatory mechanism there is need to establish special institutions framework responsible to implement the law and that there should be clear regulations that provide specifically the role of each institution.