Autoimmune diseases occurring concurrently with myelodysplastic syndrome (MDS) with deletion del(5q) including band q31 are very rare and have only been reported twice in the medical literature. We present two additional cases, one patient with del(5q) and trisomy 21 who suffered from rheumatoid arthritis and one patient with isolated del(5q) and autoimmune hemolytic anemia. Both patients had mild leukopenia and severe transfusion-dependent anemia. The rheumatoid arthritis was treated with antirheumatics without additional immunosuppressive medication. Autoimmune hemolytic anemia was controlled with long-term steroid administration. This patient developed additional trisomy 21 2 years after the initial diagnosis of del(5q). Contrary to previous reports on autoimmune disorders in MDS mentioning improvements of hematological function in response to steroid administration, neither of our patients had a hematological improvement under corticosteroids.