Body proportions were studied in 31 girls with constitutional tall stature during treatment with 200 micrograms ethinyl oestradiol per day continuously, combined with 5-10 mg medroxyprogesterone on the first 10 days of each month. Their mean (+/- SD) predicted adult height was 186.0 (+/- 4.0) cm. At the start of therapy, leg length (LL) standard deviation score (SDS) (3.8 +/- 0.7) was significantly greater than the sitting height (SH) SDS (2.3 +/- 1.1). During therapy, the mean sitting height increased by 2.9 cm, in contrast to an increment of only 0.8 cm for LL. The SDS of the ratio between SH and LL remained below zero. The expected gain without therapy, assuming a stable SDS position over time, was 5.4 cm for SH and 4.4 cm for LL, significantly more than the observed gains. In conclusion, tall girls have relatively long legs. Oestrogen therapy leads to an almost complete stop of leg growth, while the growth of the trunk is reduced to a lesser extent. This selective inhibition results in a trunk/leg ratio which is closer to, though still significantly different from that of normal girls.