Modern contraceptive methods are associated with extreme disturbances of the 'normal' menstrual pattern. Such disturbances are likely to influence a woman's decision to discontinue contraceptive use and affect overall contraceptive acceptability. In an attempt to understand the impact of hormonal contraceptives on vaginal bleeding, the World Health Organisation sponsored a series of multicentre clinical trials comparing a wide range of contraceptive methods. The data were collected on menstrual diary cards and consisted of daily records of vaginal bleeding experiences of women using a given contraceptive method. Records were up to two years long. The principal aims of the analysis are to investigate differences in the experience of vaginal bleeding disturbances in women using different contraceptive methods and also in the risk of discontinuing these methods, for bleeding-related reasons. Five cultural groups are compared: Europe, Latin America, Africa, India/Pakistan and East/SE Asia. The results show substantial differences between these groups, in the hazard of contraceptive discontinuation for various reasons. In particular, women from East/SE Asia are found to be much more likely than Europeans to discontinue use of intravaginal contraceptives, due to vaginal bleeding problems. The hazard of contraceptive discontinuation is seen to peak in the second three months of use and this is most apparent for discontinuations due to bleeding-related problems. This pattern in the hazard highlights the impact of vaginal bleeding disturbances in the earlier stages of contraceptive use. Results from the analysis are important in advising women from different cultural backgrounds in the choice of contraceptive method and in improving the benefits of contraceptive counselling.