We recently proposed MultifacetedProtDB (https://multifacetedprotdb.biocomp.unibo.it), a curated database providing a collection of 1103 multifunctional human proteins, of which 812 are enzymes. The characterization of multifunctional proteins is an expanding research area aiming to elucidate the complexities of biological processes. In our resource, we merge information from UniProt, Humsavar, Monarch, and ClinVar, reporting disease nomenclatures as MONDO, ICD10, OMIM and Orphanet catalogues. Some 30% of multifunctional proteins in our database (321 enzymes and 110 non-enzymes) are associated with 895 MONDO diseases classified into 213 ICD10 categories and in 17 out of the 19 ICD10 main chapters. Out of the 895 diseases, 323 are included in the Orphanet catalogue of rare diseases. Over the 431 multifaceted proteins with MONDO disease annotation, 212 are associated with multiple diseases, and 56% are associated also with multiple Reactome pathways. Performing different functions in different pathways could explicate why a protein is associated with different diseases. Thanks to the “ADVANCED SEARCH” interface in MultifacetedProtDB, it is possible to search for multifunctional proteins associated with MONDO diseases and endowed with Pfam annotations, obtaining as a result a list of 428 entries. Specifically, the Protein kinase domain (PF00069), the Cytochrome P450 domain (PF00067), the Connexin domain (PF00029) and the β/γ crystallin domain (PF00030) are most frequently associated with diseases in multifunctional proteins. Presently, data in our DB indicate that multifunctionality is not exclusively related to multiple subcellular locations, and/or association with diseases, and that some multifunctional proteins with specific domains seem more involved than others in diseases.