The Camberwell Psychiatric Register was searched for contacts by the 2257 women resident in the register catchment area who were known to have had a child in 1970. Of these, 99 women (and 39 of their husbands) were found to have had a 'new episode' of psychiatric illness in the two years before or the two years after the birth of their child. The distribution of these 'new episodes' relative to the time of childbirth was then studied. In the women, both functional psychoses and depressive illnesses showed a sharp rise in the new episode rate in the three months immediately after delivery. There was also a suggestion of a secondary rise, less dramatic but more sustained, from the 10th to the 24th month after delivery. There was no comparable rise in the husbands. Women whose children were illegitimate had high new episode rates throughout the four-year study period, but not particularly so in the puerperium itself.