In this work evaluation of usefulness of monoclonal antibodies (MAbs) CCH2 and AAC10 directed against early - pUL44(DB52) and late - ppUL83(pp65) CMV antigens, utilized in Department of Virology, NIH for routine diagnosis of CMV infection by shell vial and pp65 antigenemia assay, for determination of CMV antigens by flow cytometry in human leucocytes, isolated, infected and cultivated in vitro was presented.