Introduction:
A case of cold agglutinin syndrome due to cytomegalovirus infection is being reported.

Aim:
To learn rare manifestation of cytomegalovirus (CMV) infection.

Case study:
Though CMV infections are not very rare in immunocompetent individuals, CMV leading to hemolytic anemia is a rare phenomenon. We report a case of cold agglutinin mediated autoimmune hemolytic anemia (AIHA) in one such patient due to CMV infection. He recovered fully without receiving steroids or antiviral therapy.

Results and discussion:
Cold agglutinin mediated AIHA accounts for 7%–25% of all causes of AIHA. The most common infections include Epstein–Barr virus and Mycoplasma pneumoniae. CMV is associated with cold agglutinin mediated hemolytic anemia predominantly in immunosuppressed individuals and children. A number of studies have indicated that CMV infection in the immunocompetent host may be more common than previously thought. It can present itself in many ways but AIHA is rare. We present this case for its rarity.

Conclusions:
CMV may also cause serious manifestations in an immunocompetent patient.