Rapid and reliable laboratory diagnosis of cytomegalovirus (CMV) infection in transplanted patients becomes more significant considering possible prevention or moderation of CMV disease. The aim of this study was comparison of CMV isolation in cell culture and CMV detection by PCR in blood and urine samples of transplanted patients. The study comprised 21 patients undergoing immunosuppressive therapy after renal or bone marrow transplantation. MRC-5 cell culture was used for viral isolation. Inoculated cultures were maintained for 4 weeks or until appearance of specific cytopathic effect (CPE). Primers used in PCR were specific for the sequence within egzon 4 of immediate-early 1 (IE-1) gene. Presence of anti-CMV IgG and IgM antibodies was determined by ELISA. PCR was more sensitive for blood (4/21) and urine samples (3/19) than cell culture method--blood (0/21) urine (2/19). Statistically significant correlation was not shown between presence of CMV(determined by PCR) in blood and urine of the same patient.