In Perth, the provision of donated expressed breastmilk through the Perron Rotary Express Milk Bank (PREM Bank) provides an alternative to formula for extremely premature babies whose mothers have an insufficient breastmilk supply. The provision of pasteurized donor breastmilk in Perth has corresponded temporally to a reduction in diagnoses of necrotizing enterocolitis in the Neonatal Intensive Care Unit. Although Holder pasteurization (62.5 °C for 30 minutes) produces a microbiologically safe product, some immunological proteins such as lactoferrin, lysozyme and secretory IgA are significantly reduced. Ultraviolet-C (UV-C) irradiation is currently being investigated as an alternative to Holder pasteurization and has been shown to preserve lysozyme, lactoferrin and secretory IgA concentrations (1). However, the inactivation of virus in breastmilk by UV-C irradiation is yet to be investigated. Around 50-70% of the fertile female population of Australia will have had an infection with cytomegalovirus (CMV) prior to conception. In nearly all of these women, latent virus will focally reactivate in their breast tissue and virus will be secreted into breast milk. For most babies, this is of no medical concern, but extremely premature babies (<28 weeks gestation) are susceptible to CMV infection via breastmilk. CMV seropositivity does not preclude a breastmilk donor from donating milk, and it is well established that Holder pasteurization inactivates any CMV that might be present in the donation. It is therefore important to establish that UV-C irradiation can inactivate CMV in breastmilk donations. We investigated optimal conditions for the successful inactivation of CMV (laboratory strain AD169) spiked into milk and determined that effective inactivation is affected by UV-C intensity and the duration of exposure. Additionally, we investigated the efficacy of freezing breastmilk at -20°C for viral inactivation, and did not find that viral titres were significantly reduced, even when milk was subjected to repeated freeze/thaw cycles. UV-C irradiation inactivates CMV in breastmilk providing further support for UV-C as a viable alternative treatment method.