The term "deciduosis" is used to describe the severe pregnancy-associated occurrence of ectopic decidua with a usually asymptomatic course. We report on two cases of massive maternal intra-abdominal bleeding due to such symptomatic changes. The complications arose at different time points for the two cases: prepartum (26th week of pregnancy) or, respectively, - reported here for the first time - seven days postpartum. As well as differential diagnostic aspects we describe the management of the disease and its possible effects on subsequent pregnancies.