Purpose: The purpose of this study is to describe the rate of cytomegalovirus (CMV) virolactia, and the prevalence of breast milk (BM)-transmitted postnatal CMV infection among premature infants after freeze-thawing (FT) and Holder pasteurization (HP) of breast milk. Methods: This is a single-center, retrospective study of 312 infants born at less than 32 weeks of gestation, or with a birth weight less than 1,500 g from January 2013 to June 2017. All infants were screened for CMV-specific immunoglobulin (Ig) G and IgM at birth. Initial CMV specific polymerase chain reaction (PCR) and CMV culture were performed on mothers' BM and babies' urine within the first 21 days of life. FT and HP of BM was used to prevent the transmission of CMV. For the surveillance of postnatal CMV infection, CMV culture and CMV specific PCR of urine from babies were repeated one to two months after the initial screening. Screening for viremia and viruria was performed if postnatal CMV infection was suspected. Results: Among 178 BM samples obtained from mothers of CMV-IgG-seropositive infants, 80 (44.9%) were CMV PCR positive. CMV deoxyribonucleic acid (DNA) was detected in five of the 22 BM samples (22.7%) obtained from the mothers of CMV-IgG seronegative infants. When CMV DNA load in BM was measured before and after HP, various results were shown. Sixty-three infants out of 232 (27.2%) were evaluated for postnatal CMV infection and four infants out of 63 (6.3%) were infected. Conclusion: Interventions to prevent BM-transmitted CMV infection can reduce the chance of postnatal CMV infection, but not completely eliminate it.