The "burned-out" phenomenon in germ-cell neoplasias is defined by the presence of an extragonadal germ-cell tumour with no tumour at the testis level where a series of distinctive histological lesions can be detected indicative of the earlier presence of an already disappeared testicle tumoration. Extragonadal germ-cell tumours with "burned-out" phenomenon show better evolution than their primary counterparts and are treated similarly to primary tumours of the testis. Currently, in the presence of retroperitoneal tumoration, a scrotal ultrasound study with high frequency transducers can lead to a suspected picture of tumoral involution. This paper contributes one retroperitoneal seminoma with "burned-out" phenomenon in the homolateral testis in a 35-year old patient. Available clinical and radiological criteria were enough to reach a suspected diagnosis. Homolateral orchiectomy and biopsy of retroperitoneal tumoration were performed, rounding treatment up with polychemotherapy. Evolution was good with immediate complete response.