In the last 20 years, in developed countries, maternal mortality rates have fallen such that analysis of cases of severe maternal morbidity is necessary to provide sufficient numbers to give a clinically relevant assessment of the standard of maternal care. Different approaches to the audit of severe maternal morbidity exist, and include need for intensive care, organ system dysfunction and clinically defined morbidities. In both developed and developing countries, the dominant causes of severe morbidity are obstetric haemorrhage and hypertensive disorders. In some low-resource regions, obstructed labour and sepsis remain significant causes of severe maternal morbidity. The death to severe morbidity ratio may reflect the standard of maternal care. Audits of severe maternal morbidity should be complementary to maternal mortality reviews.