Introduction Perfusion differences related to posture/position and arterial blood pressure (BP) in the upper and lower limbs are long known. Some pathologies, such as critical limb ischemia, diabetes, and peripheral vascular disease, accentuate these differences. Variations between left and right lower limb perfusion during rest were reported in healthy subjects in the upright position. Although poorly understood, recent studies have suggested that anatomical and morphometric asymmetries of femoral arteries in paired legs could explain these haemodynamical differences. Our recent observations suggest that these might result from various factors other than BP. Aims/objectives To analyze the association of sex, age, and body mass index (BMI) with perfusion asymmetries of the lower limbs. Methods Perfusion was measured with LDF (laser Doppler flowmetry) at the 3rd metatarsophalangeal dorsal region in both feet. 139 healthy participants of both sexes were recruited. Age, BP (systolic – SYS; diastolic – DIA), height, and weight were taken. Measurements were obtained in supine and upright position. Procedures respected all the principles of good clinical practice for human studies research. Participant data was grouped into Young ( 30 years old), and BMI categories (Normal weight 0.05). Individuals in the supine position had significantly higher ratios (p=0.002). Considering mean LDF for perfusion assessment, significant differences were observed regarding sex (higher in males, p=0.013), age (higher in adults, p<0.0001), and BMI (higher in overweight, p<0.0001). Logistic regression models showed that BMI had a higher impact than sex or age on perfusion (Q4/Q1 – aOR 4.37 [1.13 – 16.95; p=0.032]). Moreover, regression models adjusted for BP, sex, age and BMI, confirmed that the body position was associated with higher ratios between limbs (High/Low – aOR 2.76 [1.27 – 5.99, p=0.010]). Conclusions Our data suggests that body position and BMI are the most important determinants for these resting lower limb perfusion differences. Future studies should focus on the relationship between dominance, perfusion and lifestyle factors with known effects e.g. tobacco use and exercise.