A woman with secondary amenorrhoea and an X long-arm deletion (pter----q21:) is described and compared with 30 adult non-mosaic, banded cases. Approximately 50% of the patients had gonadal dysgenesis associated with a higher frequency of short stature and "Turner stigmata" than in women with indication of ovarian activity. It is suggested that preservation of bands Xq26----28 may be decisive for normal ovarian function.