The relationships between HIV infection, monocyte activation, and endothelial colony forming cells (ECFCs) are unknown. We compared ECFC, intermediate monocytes (CD14CD16), and non-classical monocytes (CD14CD16) levels in HIV-infected participants virologically-suppressed on antiretroviral therapy, HIV-infected treatment-naïve participants, and HIV-uninfected healthy controls. ECFC levels were significantly higher in the HIV-infected, virologically-suppressed group compared to the uninfected controls. CD14CD16 percentages (but not CD14CD16 cells) were significantly higher in both HIV-infected groups vs uninfected controls. In the HIV-infected groups, ECFCs and CD14CD16 intermediate monocytes were significantly and inversely correlated. Lower availability of ECFCs may partly explain the relationship between greater intermediate monocytes and atherosclerosis in HIV.