The Macromolecular Interactions Facility (MIF) in the Department of Biochemistry and Molecular Biology at the Bio21 Institute, University of Melbourne, is a collaborative platform technology resource for the biophysical characterisation of proteins and other macromolecules. It offers state-of-the-art instruments for the analysis of protein size, shape, secondary structure, interactions and complex formation, including analytical ultracentrifuges, a circular dichroism spectrometer, isothermal titration calorimeter, biolayer interferometer and fluorescence spectrometer. The analytical capabilities of these instruments have been successfully exploited for the study of ligand binding and intracellular aggregation processes, and have also been extended beyond proteins to nanoparticles and other systems. Our equipment is open to all academic and commercial users on a pay-per-use system, and training can also be provided.