Abstract: The aim of this study was to analyse the association between human immunodefciency virus (HIV) related clinical and analytical parameters and the presence of subclinical atherosclerosis as well as endothelial dysfunction. This was a prospective cohort study of HIV-positive patients who underwent intima media thickness (IMT) determination and coronary artery calcium scoring to determine subclinical atherosclerosis. To detect endothelial dysfunction, the breath holding index, fow-mediated dilation and the concentration of endothelial progenitor cells (EPCs) were measured. Patients with an IMT? 0.9 mm had an average of 559.3 ± 283.34 CD4/?l, and those with an IMT< 0.9 mm had an average of 715.4 ± 389.92 CD4/?l (p= 0.04). Patients with a low calcium score had a signifcantly higher average CD4 cell value and lower zenith viral load (VL) than those with a higher score (707.7 ± 377.5 CD4/?l vs 477.23 ± 235.7 CD4/?l (p= 0.01) and 7 ×?¬104 ± 5 ×?¬104 copies/ml vs 23.4 × 104 ± 19 × 104 copies/ml (p= 0.02)). The number of early EPCs in patients with a CD4 nadir< 350/ µl was lower than that in those with a CD4 nadir? 350 (p= 0.03). In HIV-positive patients, low CD4 cell levels and high VL were associated with risk of developing subclinical atherosclerosis. HIV patients with CD4 cell nadir < 350/µl may have fewer early EPCs.