A system and method for lysing of whole blood for CO-Ox measurement uses a lysing chamber for acoustic lysing of whole blood in a module in which the lysing chamber is separate from a CO-Ox measurement chamber. The disclosed acoustic lysing system and method avoids the expense and complexity of chemical lysing methods and allows the whole blood sample to be lysed while under continuous flow through the lysing chamber. The acoustic lysing chamber is provided upstream from a CO-Ox measurement chamber. The separation of the lysing chamber from the Co-Ox measurement chamber provides freedom to arrange and orient various optical components and/or other CO-Ox measuring components around the CO-Ox measurement chamber. The decoupling of the lysing chamber from the CO-Ox measurement chamber allows for more efficient design of the ultrasonic lysing transducer and CO-Ox measurement optics.