Abstract: 【Abstract】 Objective To evaluate the value of indirect immunofluorescence on salt-split skin （IIF-SSS） in the diagnosis of bullous pemphigoid （BP）. Methods A single-center clinical retrospective study was conducted. Totally, 163 patients with newly diagnosed BP were collected from Hospital of Dermatology, Chinese Academy of Medical Sciences from January 2013 to January 2019, so were 404 controls, including 161 with pemphigus, 67 with eczema, 26 with drug eruption, 23 with erythema multiforme, 18 with prurigo nodularis, etc. Blood samples were collected before the treatment, and IIF-SSS, BP180 NC16A enzyme-linked immunosorbent assay （ELISA） and direct immunofluorescence （DIF） assay were performed to evaluate the value of IIF-SSS in the diagnosis of BP. Measurement data were compared by using t test and Mann-Whitney test, and enumeration data were compared by using chi-square test and Fisher′s exact test or McNemar test. Results The number of cases positive for IIF-SSS, BP180 NC16A ELISA and DIF assay was 160, 153 and 127 respectively in the BP group, and 0, 18 and 26 respectively in the control group. The sensitivities of IIF-SSS, BP180 NC16A ELISA and DIF assay for the diagnosis of BP were 98.15%, 93.86% and 77.91% respectively, and their specificities were 100%, 95.54% and 93.56% respectively. There was strong consistency in the diagnosis of BP between IIF-SSS and DIF （Kappa coefficient = 0.767, P < 0.001）. Conclusion IIF-SSS has relatively high sensitivity and specificity for the diagnosis of BP, and can serve as a routine method for diagnosing BP.

Key words: Pemphigoid, bullous, Diagnosis, Fluorescent antibody technique, Enzyme-linked immunosorbent assay, Indirect immunofluorescence on salt-split skin