Importance: Mucous membrane pemphigoid (MMP) is a rare, heterogeneous subepithelial autoimmune bullous disease. The association between its clinical and immunological features is yet to be fully evaluated. Objectives: To characterize the clinical, immunoserological, and immunopathological characteristics of patients with MMP and to identify site- and autoantigen-specific characteristics. Design, Setting, and Participants: A retrospective cohort study encompassing all consecutive patients diagnosed with MMP from January 2007 through February 2020 in 2 tertiary referral centers in Germany. Main Outcomes and Measures: The clinical, immunoserological, and immunopathological features of eligible patients were evaluated. Associations of different anatomical sites and autoantigens were assessed using a multivariable logistic regression model. Results: The study encompassed 154 patients (96 [62.3%] women and 58 [37.7%] men; mean [SD] age at diagnosis, 66.2 [13.8] years) with MMP, of whom 125 (81.2%), 61 (39.6%), 34 (22.1%), and 16 (10.4%) presented with lesions involving the oral, ocular, nasal, and genital mucosae, respectively, and 35 (22.7%) presented with cutaneous involvement. Among the 154 patients, the most frequently targeted antigen was BP180 (90 patients [58.4%]), followed by laminin 332 (13 patients [8.4%]) and BP230 (3 patients [1.9%]). Ocular disease was inversely associated with oral (adjusted odds ratio [aOR], 0.02; 95% CI, 0.01-0.13) and nasal (aOR, 0.20; 95% CI, 0.04-0.91) involvement and was associated with a 13-fold increased risk of malignant neoplasm (aOR, 13.07; 95% CI, 1.56-109.36). Anti-laminin 332 reactivity was associated with malignant neoplasm (aOR, 23.27; 95% CI, 1.83-296.68), whereas anti-BP180 NC16A immunoglobulin G seropositivity was associated with absence of ocular lesions (aOR, 0.09; 95% CI, 0.01-0.99). Conclusions and Relevance: In this cohort study of patients with MMP, malignant neoplasms were associated with ocular disease and anti-laminin 332 reactivity, suggesting potential benefit of malignant neoplasm screening in these patients.