Background: Stage I testicular germ cell tumor (TGCT) has excellent cure rates and surveillance is fully included in patient’s management, particularly during the first years of follow-up. Surveillance guidelines differ between the scientific societies, with different recommendations concerning clinical and imaging frequency de-escalation and long term follow-up. We evaluated surveillance practice and schedules followed by French specialists and set up a DELPHI method to obtain a consensual surveillance program with an optimal schedule for patients with localized TGCT. Methods: An online survey on surveillance practice of stage I TGCT based on clinical-cases was conducted among urologists, radiotherapists and oncologists. Results were compared to AFU, ESMO and EAU guidelines. Then a panel of experts assessed surveillance proposals following a formal consensus method (DELPHI method). Statements were drafted after analysis of the previous survey and systematic literature review, with 2 successive rounds to reach a consensus. Results: Survey and DELPHI method were conducted between July 2018 and May 2019. 61 participated to the survey (69% oncologists, 15% urologists, 16% radiotherapists). About 65% of practitioners followed clinico-biological guidelines concerning 1 to 5 years of follow-up, only 25% discontinued surveillance after the 5th year, as recommended. No physician followed the ESMO guidelines of de-escalation chest imaging. A panel of 32 experts (78% oncologists, 16% urologists, 6% radiotherapists) was asked about 38 statements. Consensus was reached for 26 statements concerning clinico-biological surveillance modalities and end of surveillance after the 5th year of follow-up. For seminoma, abdominal ultrasound was proposed as an option to the abdominopelvic (AP) scan for the 4th year of follow-up. No consensus was reached regarding de-escalation of chest imaging. Conclusions: The survey proved that French TGCT specialists do not follow current guidelines. With DELPHI method, a consensus was obtained for frequency of clinico-biological surveillance, discontinuation of surveillance after the 5th year and discontinuation of AP scan on the 4th year of follow-up for seminoma. Questions remains concerning type and frequency of chest imaging.