It is not well established whether haemorheological alterations constitute independent risk factors for deep vein thrombosis (DVT).We have determined in 149 DVT patients and in 185 control subjects the body mass index (BMI), the haemorheological profile: blood viscosity (BV), plasma viscosity (PV), fibrinogen (Fg), erythrocyte aggregation (EA), erythrocyte deformability (ED) and plasma lipids. In the crude analysis BMI, Fg, PV, EA, triglycerides (TG) and ApoB were statistically higher and HDL cholesterol (HDL-Chol) statistically lower in DVT patients than in controls. No differences in BV and ED were observed.After BMI adjustment, Fg, PV and EA remained statistically higher in DVT cases than in controls (P=0.013; P=0.012; P=0.013; P=0.028, respectively). When the risk of DVT associated with these variables (using cut-offs that corresponded to the mean plus one SD of the control group) was estimated, EA>8.2 and PV>1.28 mPa.s were significantly associated with DVT even further adjustment for lipids and obesity (OR=2.78, P=0.004; OR=1.91, P=0.024, respectively). However, PV did not remain statistically significant after additional adjustment for Fg.When we consider together all the analyzed variables in order to control every variable for each other,TG>175 mg/dl (OR=3,2,P=0.004) and BMI>30 kg/m2 (OR=3.5, P=0.003), were also independently associated with a greater risk of DVT. Our results suggest that increased EA constitute an independent risk factor for DVT. However, when associated to hyperlipidaemia and obesity it further increases thrombotic risk.