Different height predictions of 48 untreated girls with constitutionally tall stature (bone age 10.0-14.0 years) were compared with the final height. The following conclusions were drawn: The height prediction according to Bayley-Pinneau provided the best results. However, by this method the final height of the younger girls is markedly underestimated while that of the older one's is slightly overestimated. Mathematical methods for correction of these errors and for estimation of the growth rates are given in the text.