The characteristics of normal labour in 1306 white, Asian and black parturients have been established following a prospective study of 3217 consecutive labours. Asian patients were found to be of significantly shorter stature than white or black women (p less than 0-001) and their infants significantly lighter than those of white (p less than 0-001) and of black (p less than 0-05) women, and a low positive correlation was found between maternal height and infant birth weight. The mean duration of the first stage of labour, taken from the time of admission to the labour ward, was 5-6 hours in primiparae and 3-7 hours in multiparae. The mean durations of the second stage of labour were 41-5 and 17-4 minutes respectively. The correlations between the duration of the first and second stages of labour were too low to be of value in patient management. Similar low correlations were found between the duration of the second stage of labour and both infant birth weight and the Apgar score at one minute. Cervical dilatation-time curves, constructed with reference to the cervical dilatation found on admission to the labour ward, revealed no significant differences in the progress of normal labour in the different racial groups.