Collagen is the most abundant component of the extracellular matrix, and therefore represents an ideal platform for culture of a variety of cell types. Collagen has been widely used in 3D culture models for tissue engineering and musculoskeletal-related research. Recently, attempts to extend the use of collagen-based 3D culture models to cancer research have shown promise. While 2D culture presents a useful tool for cancer research, it is ultimately flawed due to poor replication of the tumour microenvironment, the lack of three- dimensional cell-cell/cell-matrix interactions and often exaggerated response to therapeutic agents. 3D models that aim to overcome the issues associated with 2D culture research offer a new frontier for cancer research with cell growth, morphology and genetic properties that more closely match in vivo cancer. The focus of this thesis was to develop 3D collagen- based scaffolds for use in breast cancer research. A range of collagen-based scaffolds were successfully fabricated using a freeze-drying procedure. Scaffolds were highly porous with homogenous pore sizes and an interconnected structure that was suitable for cell infiltration and nutrient/waste exchange. All scaffolds demonstrated appropriate mechanical properties for mimicking cancerous breast tissue stiffness and displayed high in vitro stability with low degradation. Cell line studies demonstrated scaffold biocompatibility with sustained breast cancer cell proliferation over 21 days, with cells fully infiltrating throughout the scaffolds. 3D culture led to an increase in cell malignancy compared to 2D, with MCF7 cells displaying properties of ECM modification, hypoxia and glycolysis. The fabricated scaffolds were successfully applied as an in vitro drug testing model, with cells cultured in the 3D scaffolds displaying increased chemoresistance compared to 2D cultured cells. Overall, this thesis successfully delivered a biologically relevant in vitro culture model that offers significant potential to deliver an increased understanding of breast cancer progression and augment drug discovery.