Background: HIV drug resistance is presumed to be inevitable due to the error-prone nature of the virus. However, poor adherence to the antiretroviral drugs is proven to be an impending factor for HIV drug resistance development. Of these two explanations, which is the most common reason for HIV drug resistance?Method: A total of 40 published studies about HIV drug resistance, were retrospectively collected in Pubmed (May 2017), from 36 different countries for this paper. From each study was participants, percentage of HIV drug resistance and HIV-1 subtype extracted for analysis. All studies were than classified by either high-income, middle-income or low-income, based on a country income status, defined by the World Bank. HIV drug resistance was tested against: continents, HIV-1 subtypes, number of study participants, income levels, GDP per capita and EWI’s. All statistical analysis was performed in R: The R project for statistical computing.Result: This paper show, that HIV drug resistance primarily is caused by poor adherence which is closely associated with drug stock out. Highest HIV drug resistance levels was found in middle-income countries. However, number of participants enrolled per study was important for the outcome and this indicates that HIV drug resistance would be higher in low-income countries if larger studied had been carried out in these settings. This means that there is a large unrecorded prevalence of HIV drug resistance in low-income countries.