In autoimmune diseases, the host’s immune system produces antibodies against antigens naturally occurring in its body. The immune response can be triggered by both own and foreign antigens. An important role in controlling an autoimmune process is played by genetic and environmental factors, including infections which may cause autoantibody production. The pathogenesis of autoimmune haemolytic anaemia, autoimmune hepatitis and aplastic anaemia involves autoaggressive processes. The case described in the present paper involves the coexistence of those three diseases in one patient. It is worth noting that they occur one after the other: once one of them goes into remission, another one starts manifesting itself. This study aims to draw attention to the possibility of coexistence of different autoaggressive diseases, the presence of significant correlations between them and the need to maintain vigilance with respect to patients in remission of an autoimmune disease.