ObjectiveRadical orchidectomy is the standard treatment for malignant testis tumours. Radical orchidectomy results in androgen deprivation, infertility and impaired psychological well-being, especially in synchronous bilateral tumours, metachronous contralateral tumours or tumour in a solitary testis. According to the European Association of Urology Guidelines, if pre-operative testosterone level is normal and the tumour volume is less than 30% of the testicular volume, organ preserving surgery can be performed. For nonpalpable tumours, organ-sparing surgery needs a precise intraoperative localization with high-frequency ultrasound, especially for nonpalpable tumours. Matherial and methodsWe report two cases of nonpalpable intratesticular tumours successfully localised using 99mmTc nanocolloid injected with intraoperative US and detected with a γ-ray detection probe. ConclusionsThis method is easily reproducible and safe for the patient. This technique could guarantee complete excision of the tumour, especially if the mass is poorly delimited