Polyautoimmunity is defined as the presence of more than one autoimmune disease in a single patient. The exact pathogenic mechanisms responsible for the coexistence of distinct autoimmune diseases within an individual have not been clearly explained. We report a case of a very young girl with the extremely rare co-existence of four distinct autoimmune diseases i.e. juvenile idiopathic arthritis, type 1 diabetes mellitus, coeliac disease and autoimmune hepatitis, recognized based on validated international classification criteria. The best to our knowledge there has been no case reporting coexistence of these particular four disorders in an individual. Moreover, all these diseases occurred during first three years of life, which also cause that case unique. Molecular studies of human leukocyte antigen (HLA) class II in our patient showed the presence of the HLA DRB1*01, HLA DRB1*03, HLA DQB1*02, HLA DQB1*05 molecules, which may suggest immunogenetic links between those autoimmune diseases. The presented case highlights the importance of active screening for other autoimmune diseases, if a patient with one autoimmune disease manifests with new or nonspecific symptoms.