Studies of the effects of female hormones on venous function have reported increased distensibility during the luteal phase of the normal menstrual cycle and during oral contraceptive use (Fawer et al. 1978) or no difference (Meendering et al. 2004). These results are based on measurements of whole limb volume changes to venous occlusion. As this includes additional tissues it may not represent venous volume accurately. Doppler ultrasound imaging (L12 – 3 probe, Philips UK) was used to investigate the effect of female hormones on the capacitance and compliance of the saphenous vein on the medial aspect of the calf of young women. Eight women (age 20 ± 2 (SD) yrs, height 166 ± 8 cm, weight 66 ± 16 kg), four not taking (NOC) and four taking (OC) oral contraceptives, were tested during the menstrual (M, days 2 – 7) and luteal (L, days 23 – 27) phases of the menstrual cycle. Subjects lay in a supine position with legs supported at heart level. Venous diameter was measured using on-line vessel border detection software (VIA Software, MD Medic) on a longitudinal image. Baseline values were taken after 10 min rest and showed no significant difference between groups (NOC M 2.84 ± 1.49 mm (mean ± S.E.M), NOC L 3.21 ± 1.99 mm, OC M 1.83 ± 0.79 mm, OC L 2.01 ± 0.34 mm, NS by repeated measures ANOVA). After 5 min venous distension (thigh cuff inflation to 60 mmHg) vein diameter increased similarly in NOC and OC women during both phases (NOC M 117.1 ± 5.4%, NOC L 116.4 ± 5.1%, OC M 126.0 ± 4.8%, OC L 118.1 ± 5.2%, NS by repeated measures ANOVA). Venous compliance (derived from the diameter-pressure relationship during thigh cuff deflation from 60 mmHg – 24 mmHg at 12 mmHg (10 s)^-1) tended to be greater in OC than NOC women during both phases (OC M 0.336 ± 0.002% mmHg^-1, NOC M 0.197 ± 0.084% mmHg^-1 and OC L 0.314 ± 0.233% mmHg^-1, NOC L 0.215 ± 0.077% mmHg^-1) although this did not reach significance. This tendency for greater compliance in the individual venous vessel in OC women is consistent with the findings of Fawer et al. (1978) in whole limbs, and may represent modifications of venous tone and/or elastic properties of the vessel wall under the influence of the constituent synthetic hormones within OCs which have a greater binding affinity to receptors than endogenous hormones (Schindler et al. 2003).