HIV infected patients treated with highly active antiretroviral therapy (HAART) may be at increased risk of cardiovascular events, particularly if based upon the use of protease inhibitors (PI). We investigated the haemostatic markers of cardiovascular risk in 115 HIV infected subjects, divided into four groups : 1) patients naïve to antiretroviral therapy (Naïve; n=34 patients), or subjects that had been on a stable combination therapy for > or =12 months with either: 2) double reverse transcriptase nucleoside analogue inhibitors therapy (2NRTI; n=26), 3) 2NRTI backbone plus a non-nucleoside analogue reverse transcriptase inhibitor (NNRTI; n=27), and 4) on a PI based regimen (PI; n=28). Forty-four healthy subjects were included as controls. Naïve as well as 2NRTI and NNRTI differed from controls for higher F1+2 (P<.0001) and FVII (P<.007) levels. When comparing PI patients with controls we observed significantly higher levels of Fbg (P=.035), FVII (P<.0001), TM (P<.0089), vWF (P=.009), and F1+2 (P<.0001). The only difference observed among the 4 groups of HIV infected patients was a significantly lower level of F1+2 in PI as compared with NNRTI patients (P=.05) At least one abnormal result was observed in > or = 90.6% of HIV infects groups, vs 43.2% of controls (P<.0001 in all cases). In conclusion, a) HIV infection per se may alter the haemostatic markers of cardiovascular risk, b) minor differences were observed among the different classes of HIV infected patients, namely between NNRTI and PI treated patients.