ObjectiveTo estimate the economic cost of substandard and falsified human medicines and cosmetics with banned ingredients in Tanzania from 2005 to 2015.DesignA retrospective review of data.SettingTanzania Food and Drugs Authority and premises dealing with importations and distributions of pharmaceuticals.Eligibility criteriaConfiscation reports of substandard human medicines, falsified human medicines and cosmetics with banned ingredients.Primary and secondary outcome measuresQuantities and costs of pharmaceutical products, costs of transportation, storage, court cases and disposal of products.ResultsThe economic cost of substandard and falsified human medicines and cosmetics with banned ingredients was estimated at US$16.2 million, that is, value of substandard medicines US$13.7 million (84.4%), falsified medicines US$0.1 million (1%), cosmetics with banned ingredients US$1.3 million (8%) and other/operational costs US$1.1 million (6.6%). Some of the identified substandard and falsified human medicines include commonly used antibiotics such as phenoxymethylpenicillin, amoxicillin, cloxacillin and co-trimoxazole; antimalarials such quinine, sulfadoxine–pyrimethamine, sulfamethoxypyrazine–pyrimethamine and artemether–lumefantrine; antiretroviral drugs; antipyretics and vitamins among others.ConclusionThe economic cost of substandard and falsified human medicines and cosmetics with banned ingredients represent a relatively large loss of scarce resources for a poor country like Tanzania. We believe that the observed increase in the quantities and the economic cost of these products over time could partly be due to the improvement in the regulatory capacity in terms of human resources, infrastructure and frequency of inspections.