BACKGROUND Although there have been many follow-up studies of severe puerperal psychiatric illness, few have been very long-term. METHODS Sixty-four subjects from 85 (75.3%) in an unselected sample of women admitted to a psychiatric hospital within 6 months of childbirth were successfully followed up a mean of 23 years (range 17-28) later. Most subjects were interviewed in detail, with further information obtained from general practice and hospital records. Data included subsequent illnesses and diagnoses, subsequent childbirth, longitudinal social function, current symptoms and social function. RESULTS Seventy-five per cent of subjects had further psychiatric illnesses, most of them unrelated to childbirth, and 37% had at least three subsequent episodes. The risk of puerperal psychiatric illness was 29% in subsequent pregnancies. At outcome interview the majority of subjects were well, with satisfactory social adjustment. Diagnoses in subsequent psychiatric illnesses showed considerable consistency with index diagnoses, with some shift to bipolar disorder. Further illnesses were less likely to occur where the index illness occurred with first child, onset was within 1 month of delivery, and where the index diagnosis was unipolar depression. CONCLUSIONS There is a high risk of subsequent non-puerperal recurrences following severe puerperal psychotic illness, showing considerable diagnostic consistency with the index episode, but with good functional outcome. Puerperal illnesses showed strong continuities with non-puerperal illnesses in these women.