Introduction Thromboembolism, notwithstanding its increasing rate in the last decade, remains a rare disorder in children. Its development is a consequence of a long and varied list of congenital or acquired risk factors. Approximately 95% of children with such a pathology have one or more underlying risk factors, the majority of them having even more than one.

Objective We would like to draw the attention on the exceptionally rare thromboembolic disorders lacking, at least at admission, risk factors for them.

Patients and methods From the relatively large list of patients admitted during a year in the clinic with thromboembolic disorder (14), we selected three patients, without personal or familial risk factors, illustrating severe life-threatening conditions, generated by an unexpectedly developed thromboembolism. An extensive workup (thrombophilia, surgery, insertion of arterial or venous catheters, surgery, immobilisation, malignancy, congenital heart disease, aso) was performed for explanation of the pathogenic background and for tackling an adapted, more efficacious therapy.

Results and discussion It is a heterogeneous group of three patients: a new-born with thrombosis of inferior cava vein extended in both renal veins, a school boy with peripheral pulmonary thromboembolism of multiple segmental and sub-segmental arteries, severe pulmonary hypertension and cardiac insufficiency NYHA IV and an adolescent with peripheral pulmonary thromboembolism with right pulmonary infarction, without pulmonary hypertension and cardiac insufficiency.

Conclusion Thromboembolism can encompass all paediatric ages, from new-borns, infants, to children and adolescents. Considering their potential severity and the relative high risk of recurrence rate an optimal diagnostic approach and therapeutical management are of life importance.