The diagnostic spectrum of Turner’s syndrome in patients from two diagnostic centres over the years 1965-1989 was studied. One hundred and thirty-five cases of Turner’s syndrome were confirmed, 72 with the 45,X karyotype and 63 with other karyotypes. Females with the 45,X karyotype were diagnosed at an earlier age (9.4 f 6.9 years; mean f SD) than girls in other groups (14.2 k 8.1 years; p = 0.0003). Twenty-eight per cent of girls with the 45,X karyotype were diagnosed before the age of 3, compared with only 9 % of the girls with other karyotypes. The major indicators of the syndrome were congenital lymphoedema, aortic coarctation, and failure to thrive. Sixty-five per cent of the girls with a karyotype other than 45,X were recognized as having Turner’s syndrome between the ages of 9 and 18 years, mainly because of growth retardation or delayed puberty. The corresponding figure for the girls with a 45,X karyotype was 40%. Growth retardation was the major indicator of Turner’s syndrome in 27% of all cases. Short stature resulted in an earlier diagnosis in the 45,X females than in the girls with other karyotypes (7.9 k 2.2 years versus 11.8 f 2.7 years; p = O.ooOo5). At the age of 18 years, when all but one case of Turner’s syndrome with the 45,X karyotype had been diagnosed, an estimated 16% of cases with spontaneous sexual maturation and menstruation with chromosomal mosaicism remain unrecognized. Turner’s syndrome may be diagnosed during the investigation of sterility or habitual abortion, or it may never be discovered. There are at least four documented cases in which women with mosaicism have given birth to a clinically healthy child.