Out of 24 spouses of women with postnatal psychiatric illness admitted to a mother and baby unit over 12 months, 12 were found to be psychiatrically ill, as defined by RDC or DSM-III criteria. The rate of psychiatric disorder was higher in these men than in a control group of men whose partners remained well after childbirth and a group of men whose partners were admitted to a psychiatric hospital with non-puerperal illness. The onset of psychiatric illness in the men typically followed admission of their wives to the mother and baby unit. Other associations with illness in the man were a history of chronic social problems, previous psychiatric episodes, and a poor relationship with his own father.