AP denotes detachment of a normally implanted placenta before the infant is delivered. The incidence rate is about 1% of all pregnancies and the recurrence rate in Scandinavia is found to be about 4%. AP is associated with a variety of factors during the pregnancy: trauma, threatening miscarriage, SGA, preeclampsia, PROM, chorioamnionitis, multiple fetuses, male fetus, congenital malformations and short umbilical cord. Various aspects concerning the mother are associated with AP: maternal age, birth order, socio-economical group, marital status, race, obstetric history, uterine tumours, chronic hypertension, diabetes and antiphospholipid antibodies. The mother’s way of life is also contributing etiologic factors: cigarette smoking, cocaine, marihuana, poor maternal nutrition and vitamin deficiency. There is no one theory explaining all risk factors and causes of AP. Inadequate trophoblast invasion in the spiral arteries is one of many theories focusing on a disturbed feto-maternal relationship. AP is primary a clinical diagnosis. The classical symptoms are vaginal bleeding, pain in the abdomen, uterine contractions and tenderness. Treatment is expectance, hastening vaginal delivery or caesarean section. The main differential diagnosis is placenta previa. AP is an important cause of perinatal death and morbidity. Maternal complications include hemorrhagic shock, coagulopathy and DIC, uterine rupture, renal failure and ischaemic necrosis in distal organs and finally death.