About 10% of women show elation and associated features of hypomania in the first 5 days following childbirth. These symptoms can be detected using a self-rating scale (the ‘Highs’) based on SADS-L criteria. This phenomenon has been confirmed using the observer-rated Comprehensive Psychopathological Rating Scale, which also revealed a high degree of related irritability. Significantly more women scoring ⩾ 8 on the Highs scale at 3 days postpartum went on to manifest depression at 6 weeks than did subjects with no psychopathology in the early puerperium. It is suggested that the ‘highs’ followed by depression may be a mild and common form of bipolar disorder.