We report five cases of OVT and review the literature on this disease. Among our patients OVT was not suspected clinically and was diagnosed by CT scanning or MRI. Ultrasound imaging, utilized in three cases, failed to detect OVT. Although this disease usually occurs after delivery, in two cases it was diagnosed before delivery. Of the two postpartum cases, one had a typical presentation and the other was asymptomatic. The final case was diagnosed incidentally 5 months after removal of an ovarian carcinoma. Our experience suggests that this disease may be underdiagnosed. More widespread use of CT scanning and MRI may lead to more frequent diagnosis of OVT. The role that clinically silent OVT may play in peripartum pulmonary embolism should be clarified.