During a 28-year period the incidence of thrombosis and pulmonary embolism (TE) in pregnancy remained practically equal (0.7%), the incidence of puerperal TE was higher (2.3%) but decreased during the last 7 years. Puerperal TE was influenced by age, mode of delivery, hypertension and prophylactic anticoagulant therapy. TE during pregnancy was not noticeably correlated with age and hypertension. TE during pregnancy and in the puerperium are closely related diseases, but their epidemiological characteristics are apparently distinct. Both are associated with a high rate of preterm deliveries and a high perinatal mortality rate.