(median 18%), and 0 to 33% (median 17%) by viral cultures, antigenemia, and PCR, respectively in these indices. PCR assay and antigenemia were performed in all patients in two studies [7, 12] . Twelve of 82 patients developed CMV infection detected by the PCR assay compared with six of the 82 patients by antigenemia. No cases of CMV infection were diagnosed solely by antigenemia. Lastly, we focused on three studies in which the PCR assay was used at least weekly because this method is currently widely utilized to monitor CMV infection; the rate of CMV infection was 32 to 33% in these studies [7, 10, 11] .