Cass Byrnes is a Professor of Paediatric Population Health, in the Paediatric Department at the University of Auckland and a Paediatric Respiratory Specialist at the Starship Children & Kidz First Hospitals.

She leads research in prevention of disease and disease progression that occurs with acute respiratory tract infection in early childhood. She seeks to improve health equity especially for M?ori and Pasifika children. Her clinical care is focussed in acute respiratory infections, bronchiectasis, cystic fibrosis and asthma.