Gonadal tumours are rare in children. Benign tumours are more frequent in girls than in boys (3 cases among 4 cases in girls and 1 case among 2 or 3 cases in boys), due to the prevalence of functional ovarian pathology (functional cysts, ovarian torsion). Whatever the clinical presentation of these tumours (mainly abdominal pain or mass in girls, scrotal mass in boys) and even before an emergency procedure, radiological investigations (abdominal x-rays, ultrasound scans) and biological ones (alpha-foeto-protein and human chorionic gonadotropin dosages) should be performed in order to precise the diagnosis. In benign tumours (mature teratoma, cystadenoma), a conservative surgical procedure (tumorectomy with ovarian preservation) should be attempted. Malignant or potentially malignant tumours (malignant germ cell tumours, stromal tumours) have an excellent prognosis, only if they are treated with a close collaboration between surgeons and oncologists.