Methods: A comprehensive literature review was carried out. PubMed, ScienceDirect, Cochrane and Embase were searched for English publications between 2000 and 2021.Results: A total of 50 articles covering quantitative and qualitative studies were included. Many studies identified poor adherence levels to antihypertensive treatment, reaching a substandard adherence rate of 41.9%, whilst most studies on the HIV-positive population reported good levels of adherence, with adherence rates of more than 90%. Being of the male gender, advanced age, low socioeconomic status and a low level of education were associated with unsatisfactory adherence rates in both groups. Within the HIV group, more participants had better knowledge concerning the extent of their disease and its required treatments. Conclusion:The results present substandard adherence levels to antihypertensives compared with antiretroviral (ARV) adherence, despite the influence of more non-adherence factors in the HIV group. The authors recommend better adherence counselling for patients with HTN during every clinic visit, regular healthcare worker training and the implementation of ART adherence programmes in patients with hypertension.