Immune-mediated hemolytic anemia (IMHA) is characterized by the destruction of erythrocytes or sometimes bone marrow erythroid precursors mediated by immunoglobulins (IgG, IgM), with or without complement (C 3). The main objectives of this study were to assess the laboratory test results of IMHA and to investigate its possible underlying causes in cats referring to the Veterinary Teaching Hospital of Tehran. The Coombs’ test (CT) was performed in 74 cats with PCV below 0.35. The test was positive in 26 cats. These positive CT cats were categorized into four groups based on the PCV ranges and type of anemia including: Group A: 9 of 26 cats had nonregenerative anemia (PCV median, 0.22) (1 feline leukemia virus positive which had erythroleukemia, 1 feline infectious peritonitis positive, 1 with Hemoplasma spp., 3 with renal failure, 2 with inflammatory disease and 1 with no diagnosis). Group B: 4 cats (PCV median, 0.31) had a regenerative anemia with severe dehydration. Group C: the other 9 cats with a normal range of PCV (median, 0.34) involved with various conditions (vaccination, parturition, acetaminophen poisoning, osteoporosis, and renal failure). Group D: the remaining 4 cats with a marginal range of PCV (median, 0.30) had a history of inflammatory disease and drug therapy. The results of this study indicated that infectious diseases and drug therapy were the main factors associated with positive Coombs’ test results.