Painless scrotal swelling must always be considered as a potential malignant testicular tumour until proven otherwise. Prepubertal testicular tumours are seldom entities, for their differential diagnosis testicular sonography is gaining increasing importance. Although, according to national and international tumour registries, most patients tend to have malignant tumours, some clinical series from paediatric centres confirm that prepubertal testicular tumours are mainly benign lesions, especially up to the age of 12 years. Testis-sparing procedures are favoured when AFP is in a normal range and testicular parenchyma is detected sonographically. Oncological principles should be applied to paediatric patients consequently, staging examinations should be requested when a definite histology is proven. Cases should be reported to national tumour registries and, in addition to close surveillance, in some cases adjuvant therapy is necessary. In addition to the clinical guidelines from the tumour registries, differential diagnosis, testis-sparing surgery and the presence of TIN in the paediatric population should be discussed.