Some women with bipolar disorder run a substantial risk of developing a puerperal psychosis, in spite of taking lithium; this is illustrated bij two case reports. In addition to well known riskfactors such as giving birth to a first child, a caesarean delivery and the lack of a partner, the severity of the bipolar disorder probably plays a role. This is perhaps also true for the presence of personality disturbances. This finding has consequences for the counselling prior to pregnancy and the guidance post partum.