The clinical, haematological, molecular and treatment data of eight paediatric patients with polycythemia vera (PV) were collected prospectively. One patient developed PV after treatment for large-cell anaplastic lymphoma. Budd-Chiari syndrome was diagnosed in two patients, necessitating orthotopic liver transplantation in one and transjugular portosystemic shunting in the other. The remaining patients presented with non-specific symptoms. Endogenous erythroid colonies were detected in all cases examined. The JAK2(V617F) mutation was found in six patients; two patients displayed JAK2 exon 12 mutations, including one novel mutation (JAK2(H538-K539delinsI)). CD177 (PRV-1) mRNA expression was increased in three of five patients tested.