Girls with Turner syndrome were divided according to age (group A 6-12 years, and group B 12-19 years) and human growth hormone (GH) dose regimen (A1 and B1, three injections/week; A2 and B2, six injections/week). All groups responded to GH, 24 IU/m2/week, with an increase in height velocity, though in the older girls, the response was comparatively poor. Therefore, the dose regimens in groups B1 and B2 were increased to 36 IU/m2/week given as six injections in both groups. This change resulted in an increase in height velocity only in group B1. During the first 2 years only, the height velocity was greater in group A2 than group A1. The conclusion is that a regimen of six injections/week is more effective than one of three injections/week in terms of initial height gain and change in predicted adult height. In girls with Turner syndrome aged over 16 years, GH therapy has no significant effect.