Abstract Objective. Segmental cystic tumours in the kidney are extremely rare in children. This study reports our experience of those tumours. Material and methods. The operative database from 1993 to 2008 of the Hospital for Children and Adolescents, University of Helsinki, was evaluated for segmental cystic renal tumours without any solid component. Patient records, imaging studies and pathology specimens were reviewed. Results. Four cases (three girls and one boy) were found; all were less than 3 years old at the time of diagnosis. All patients underwent kidney-preserving surgery with resection of the cystic tumour. Two patients had neoplasias: one cystic nephroma and one cystic partially differentiated nephroblastoma. Both of these patients had associated or predisposing disease (type I cystic pleuropulmonary blastoma of the lung and mulibrey nanism, respectively). Two patients had a non-neoplastic tumour; localized cystic disease of the kidney and segmental adult type autosomal dominant polycystic kidney disease. Neoplastic cystic tumours had a fibrous capsule in preoperative magnetic resonance imaging and also in operation, unlike non-neoplastic lesions. Conclusions. Preoperative and perioperative diagnosis is difficult in cases of segmental cystic kidney tumours in a child. If a neoplastic tumour is suspected complete resection of the tumour is mandatory.