Abstract
Summary: Nine cases of retroperitoneal haemorrhage complicating anticoagulant therapy are reported. Six cases were receiving heparin for myocardial infarction: an incidence of 4·3% of patients on such treatment. All the cases presented with pain, six had neurological involvement and one patient died. The incidence of this complication is higher than previously noted. Retroperitoneal haemorrhage requires a high index of clinical suspicion for early diagnosis and treatment if serious sequaelae are to be prevented.