Greenland is a high-income country with free access to human immunodeficiency virus (HIV) care, including highly active antiretroviral therapy (HAART). We aimed to examine the HIV prevalence, age and gender distribution, and the effectiveness of HAART on CD4 positive cell count, viral load (VL), and mortality in the Greenland HIV-infected population. In this population-based cohort study we collected demographic, clinical and biochemical data on all HIV-infected patients followed in health clinics since 1995. For each case, we identified 100 age- and gender-matched population controls. The HIV cohort included 103 patients of whom 91% were Inuit; 81% were infected heterosexually. Only 40% of the patients had a VL <400 copies/ml at 48 weeks after starting HAART, and patients on HAART had a substantial excess relative mortality compared with the general population (mortality rate ratio [MRR]: 10.6; 95% confidence interval [CI]: 6.9-16.4). After the introduction of HAART, the mortality decreased (MRR: 2.5; 95% CI 0.9-6.8), but remained high with a mortality rate of 62 per 1000 person-years (py) (95% CI 29-129). Our findings underline the difficulties of implementing successful HIV treatment even with unlimited economic resources and free access to health care.