In paediatrics, sick preterm infants are at highest risk of developing thrombotic complications. Haemostasis is in a fine balance in the neonatal period, despite age-related differences in coagulation proteins. However, both inherited and acquired risk factors can disrupt this balance and can lead to thrombosis. Important risk factors are sepsis, asphyxia, dehydration, central venous lines and inherited and acquired thrombophilia. Among various treatment modalities, anticoagulation is primarily used in the management of thrombosis. Different agents, dosages and durations of treatment in this age group are extrapolated from adult data. The article reviews the epidemiology, pathophysiology, risk factors, diagnosis and treatment of thrombotic disorders in preterm infants.