Oedema is considered a key pathogenic factor in the development of venous leg ulcers. The purpose of this study was to determine the localization of oedema in legs with ulcers. Twelve patients with 13 venous leg ulcers (one bilateral), with a duration of 7-18 months, were examined by high-frequency B-mode ultrasound scanner. This was performed at three sites in the leg (low, middle and upper sites of the lower leg). In the same group of patients, the legs without ulcers were used as controls. The echogenicity and the thickness of the whole dermis were quantified by digital image analysis; the echogenicities of the upper (papillary) and lower portions of the dermis were measured. In the upper site no significant difference was found between the legs with ulcers and controls. In the middle and low sites of legs with ulcers, the dermal echogenicities were 34% and 64% (P < 0.01) less than those in controls, and the dermal thicknesses were 0.4 mm and 0.8 mm (P < 0.01) thicker than those in controls, respectively. This indicated intradermal oedema existing in the lower part (gaiter area) of the legs with ulcers. The ratios of low echogenic pixels in the upper and lower portions of the dermis, in the middle and low sites of legs with ulcers, were 0.5 and 0.9 (P < 0.05 and P < 0.01), respectively, higher than those in controls, suggesting the papillary dermis as a preferential site of oedema formation. The present study demonstrates that in the low sites of legs with ulcers, a marked increase in oedema was seen in the papillary dermis. This may add to the understanding of the origin of leg ulcers in the gaiter area of the leg.