The Hippocratic maxim, "Do no harm," is a long-standing fundamental principle of medical ethics, encompassing both medical practice and medical research. Yet, not enough attention is given to the implications of this principle for sectors related to medical research and practice, such as the pharmaceutical sector. The regulation of the standards of quality in pharmaceutical production and distribution, for instance, is generally considered a purely technical – rather than ethical – subject. Poor enforcement of regulatory supervision of manufacturers and wholesalers of medicine exposes the end-users to low-quality pharmaceutical products, which will result in avoidable "harm", such as therapeutic failure, emergence of resistance and even direct toxicity. A glaring example of this in recent times was the death, in Pakistan, of 120 cardiovascular patients who had received a medicine contaminated with pyrimethamine. Due to the globalisation of the pharmaceutical supply chain and the lack of international regulatory oversight, stringent drug regulatory authorities in affluent countries are also exposed to challenges related to quality. In the USA, for instance, at least four patients died after using contaminated heparin from China. These and other unnecessary deaths, caused by medical products which harmed rather than benefited the patients, are unacceptable and should be questioned on ethical grounds.