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Introduction Sarcoidosis frequently involves intrathoracic lymph nodes and lung parenchyma and requires histological confirmation for diagnosis. Although endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is recommended for obtaining mediastinal samples, its diagnostic yield frequently necessitates additional transbronchial lung biopsy (TBLB) and/or endobronchial biopsy (EBB). EBUS transbronchial mediastinal cryobiopsy (EBUS-TBMC) can yield larger, well-preserved tissue samples than EBUS-TBNA alone. However, whether EBUS-TBMC alone is equivalent to conventional multimodal sampling (EBUS-TBNA combined with TBLB and/or EBB), and whether TBLB and EBB provide incremental diagnostic value when added to EBUS-TBMC, is still unclear.Methods and analysis In this study, 410 patients with suspected stage I/II sarcoidosis will be randomly assigned in a 1:1 ratio to either the EBUS-TBMC or EBUS-TBNA group. All participants will then undergo TBLB and EBB. The primary outcome will be the granuloma detection rate. The diagnostic sensitivity, negative predictive value and procedure-related complications will be selected for secondary outcomes. Statistical analysis will be performed using SPSS V.24.0, with non-inferior testing for the primary comparison.Ethics and dissemination Approval for this DETECTION-SAR-II trial was obtained by the China-Japan Friendship Hospital Ethics Committee (Ethics number: 2025-KY-075). Participants will be fully informed of objectives, protocol and potential risks of the study before enrolment and will provide written informed consent.Trial registration number NCT07246876.