Its high diagnostic accuracy, rapidity, quantitative nature and techni
cal simplicity have made the cytomegalovirus (CMV) antigenaemia assay
one of the cornerstone methods for diagnosis and management of active
CMV infection in immunocompromised patients. Many technical variations
have been introduced in an effort to optimize the assay. Now, standar
dization of the assay and quality control are becoming of increasing i
mportance. In this review we first discuss the nature and origin of th
e CMV antigens in distinct blood cells during active CMV infection. Fu
rther, some of the most important technical variations of the assay ar
e considered and a proposal for standardization is made to indicate ho
w quality control might be achieved. Acceptance of these proposals by
the international community would be an important step forward, e.g. t
owards multicentre antigenaemia-directed intervention studies.