PIP: Responses to questions relating to breastfeeding in the World Fertility Surveys of South Korea, Indonesia, Nepal, Sri Lanka, Malaysia, and Bangladesh are analyzed. Of these countries, the percentage of ever-married women who had breastfed in the last closed interval was between 94-99%, except for Malaysia (81%) and average number of months breastfeeding took place was from 16.5-19.2, except for Malaysia (7.3). The infant mortality rate in these countries was 33/1000 live births for South Korea, 45/1000 for Malaysia, 51/1000 for Sri Lanka, 137/1000 for Indonesia, 150/1000 for Bangladesh, and 152/1000 for Nepal. Responses, however, might vary according to different interview situations. Assuming that the reporting errors are of similar magnitude and direction, the relationship between duration of breastfeeding and the birth interval can be studied. But it is possible that breastfeeding was prolonged due to other reasons for which conception was delayed; thus the regression of breastfeeding duration on the birth interval is not as logical as the regression of the birth interval on the breastfeeding is, especially when habitual breastfeeding can be avoided. The negative relationship between breastfeeding and infant mortality does exist, assuming that a woman breastfeeds all her children for similar durations. Some breastfeeding differentials are place of residence (less for rural areas), education (reduces duration), and religion (Christians have shorter duration than Muslims, Hindus, or Buddhists). In South Korea the mean length of breastfeeding of women aged 25-34 and 35-44 are 17.5 and 20.5, and women using contraceptives are 26% for 25-34 and 20% for 35-44. South Korea also has the highest level of breastfeeding, highest incidence of ever use of contraceptives, and a very low level of fertility. Nepal and Bangladesh have a high level of breastfeeding but since their contraceptive incidence is low, their fertility level remains high. Some areas of further research include influence of breastfeeding on infant and child mortality.