Elevated permeability of the arterial wall to circulating macromolecules is implicated in the development of atherosclerotic lesions. Lesions occur near branches, suggesting a role for haemodynamic wall shear stress, and in both human and rabbit aortas their distribution changes with age. To assess the relationship between lesion development and arterial wall permeability, we used a novel high-throughput technique employing tile-scanning confocal microscopy to systematically quantify macromolecule uptake around branch ostia in the rabbit aorta at different ages. Rhodamine-labelled albumin was administered intravenously via the marginal ear vein to New Zealand white rabbits aged 2, 6 and >12 months (n>4 rabbits/group) and allowed to circulate for 10 minutes. Via the same route an anticoagulant (heparin), followed by an overdose of sodium pentobarbitone (0.8ml/kg) were given. The aorta was fixed post mortem under physiological pressure, excised and scanned en face using confocal microscopy. Tracer concentrations in the inner 10µm of the wall were mapped using MATLAB® and scaled to plasma tracer concentrations. Intensity data were statistically analysed using a nested ANOVA, and mass transfer coefficients were calculated. In young rabbits, tracer uptake was greater downstream of intercostal branch ostia than upstream. This pattern significantly reversed with increasing age – by 6 months the majority of tracer uptake localised lateral to the branch mouth and by 12 months downstream regions showed the least uptake. (Downstream-upstream)/mean uptake values were significantly different between 2 month versus both 6 month and >12 month animals (p<0.001). In young animals, the downstream mass transport coefficient was 1.5 times the upstream value (2.52±0.24×10-8cm/s vs 4.06±0.26×10-8cm/s). Mass transfer coefficients around the branch mouth averaged 3±0.3×10-8cm/s for all ages. Our results demonstrate changes in permeability patterns that parallel the age-related patterns of lipid deposition seen in rabbit and human aortas, supporting a critical role for permeability in atherogenesis. Our new tile-scanning confocal method can easily image the whole aorta and provide permeability data to compare with shear stress data and lesion maps.