Background: The standard of treatment of stage I MOGCTs is surgery followed by BEP (bleomycin + etoposide + cisplatin) chemotherapy, except for stage IA dysgerminoma (D) and IAG1 immature teratoma (IT). Surveillance has emerged as a possible option to avoid adjuvant chemotherapy in IB-C1 D, IA-C G2 – G3 IT, and in stage IA mixed and yolk sac tumors (YST), after comprehensive surgical staging (CSS) with negative postoperative markers. The aim of this study was to analyze oncological outcome of stage I MOGCT patients included in the MITO9 study. Methods: MITO9 was a prospective observational study analyzing data collected between 2013 and 2018. 41 patients with stage I conservatively treated MOGCTs were included. Three groups were identified: group A. IA D and IAG1 IT candidate to surveillance according to guidelines; group B. stages IB-C1 D, stage IA-C G2-G3 IT, stage IA mixed and YST were consulted about the option of close surveillance vs adjuvant chemotherapy in case of CSS; group C. all other patients receiving BEP. Results: Median age was 25.6 years (range 14-40). Median follow up was 36,4 months. Group A included 12 patients, 5 IA G1 IT and 7 IA D. Group B included 24 patients. Of these, 2 out of 5 patients (40%) were positive at restaging and were excluded from surveillance protocol. Seven of the 22 remaining patients (31.8%) received chemotherapy, while 15 (68.1%) were enrolled in the surveillance protocol. Out of these 15 patients, 4 were stage IC D (one IC1, one IC2 and two IC3), 2 were mixed stage IA with YST tumor, 9 were G3 IT (four IA, three IC2, one IC3 and one IB). The 7 patients receiving chemotherapy were: 1 dysgerminoma IC2, 2 YST IA, 3 IT G3 (one IA and one IC2) and 1 mixed IA tumour. Group C included 5 patients, three IC YST and two mixed IC2 with YST. Survival of these patients was 100%, while disease free survival was 97.5%. Only one patient in C Group, a stage IA G3 IT treated with adjuvant BEP, relapsed as mature teratoma. None of the patients in the surveillance protocol experienced relapse. Conclusions: These data suggest that close surveillance could be an alternative option to avoid adjuvant chemotherapy in properly staged IB-C1 D, stage IA G2 – G3 IT, stage IA mixed and YST. These findings deserve further confirmation in an international cooperative setting.