The incidence of thrombo-embolic complications in pregnancy varies between 2 and 5 per 1000 deliveries. Deep-vein thrombosis (DVT) is classically associated with pulmonary embolism and chronic venous insufficiency, which are leading causes of maternal morbidity and mortality. An accurate diagnosis of iliofemoral or calf vein thrombosis should be confirmed by either Doppler ultrasonography, impedance plethysmography or ascending phlebography. Full-dose continuous intravenous heparin for 5-10 days is the established method of therapy for acute DVT and pulmonary embolism occurring during pregnancy or in the puerperium. Thereafter, long-term treatment with self-administered subcutaneous injections of heparin in low doses is feasible and effective. During pregnancy, coumarin administration results in embryopathy as it readily crosses the placenta; it should be avoided until after delivery. In view of its safety and effectiveness, low-dosage intravenous heparin or heparin by subcutaneous injection seems to be the anticoagulant of choice for the expectant mother.