A Serous Tubal Intraepithelial Carcinoma (STIC) without concomitant invasive carcinoma is occasionally identified and associated with a high risk of subsequent peritoneal carcinomatosis. Management needs optimisation. This study explores professionals' opinions and clinical practices regarding the diagnosis, counselling, treatment and follow-up of isolated STIC to facilitate clinical decision making and optimise the direction of future research. A secondary aim is to assess international clinical guidelines. Focus group study. Four online sessions. International panel (n = 12 countries) of gynaecologists, gynaecologic oncologists, pathologists and medical oncologists (n = 49). A semi-structured interview guide was used. Two independent researchers analysed transcripts by open and axial coding. Results were organised in domains. Relevant (inter)national guidelines were screened for recommendations regarding isolated STIC. Professionals' opinions and clinical practices regarding isolated STIC management. Regarding pathology, most professionals identified the SEE-FIM protocol as standard of care for high-risk patients, whereas variation exists in the histopathological examination of fallopian tubes in the general population. Confirmation of STIC diagnosis by a specialised pathologist was recommended. Regarding work-up and follow-up after STIC diagnosis, there was variety and discordance. Data on outcomes is limited. As for treatment, chemotherapy and PARP inhibitors were not recommended by most. Eleven guidelines provided limited recommendations. We identified recommendations and highlighted knowledge gaps in the diagnosis and management of isolated STIC. Moreover, recommendations in clinical guidelines are limited. There is an agreed need for international collaboration for the prospective registration of isolated STIC.