Since the pioneering work of Donald and his first Lancet paper in 1958, the use of ultrasound in obstetrics and gynaecology has evolved rap idly. The introduction of grey scale techniques enhanced our ability to identify different tissues on the basis of their texture. However, it was the introduction of the linear array real-time scanner in the mid seven ties that changed ultrasound from being an eccentric art form to a readily available and usable technique. This led to the first reports of the diagnosis of neural tube defects using ultrasound by Campbell, as well as the establishment of fetal biometry. In the midst of this activity the parallel development of the transvaginal probe by Kratochwill went almost unnoticed by most gynaecologists. Yet the application of this technique has since had a major impact on many areas of gyna ecological practice, and on infertility in particular. Since the demon stration of transvaginal follicle aspiration, the vaginal route has become standard for most invasive ultrasound guided gynaecological procedures. The relatively new technical advance of transvaginal colour Doppler may potentially have just as great an impact. The introduction and use of transvaginal colour flow imaging has facili tated the study of vascular changes within the pelvis.