Non-animal testing methods are increasingly being adopted in scientific research, propelled by the principles of the 3Rs—Replacement, Reduction, and Refinement. Among these alternative approaches, the Monocyte Activation Test (MAT) has emerged as a promising New Approach Methodology (NAM) in immunotoxicology. This assay uses primary human monocytes to provide a human-relevant, innovative means to assess immune responses without the use of animal models. In doing so, it addresses growing ethical and regulatory imperatives for more humane research practices. MAT is particularly useful for detecting and quantifying both endotoxin and non-endotoxin pyrogenic contaminants in parenteral products and can also be applied to certain medical devices that come into contact with sterile body sites. This webinar will present an overview of MAT’s underlying principles, its potential as a reliable and efficient NAM, its current regulatory landscape, and practical applications. Looking ahead, we will explore MAT’s potential role in broader safety testing strategies and its capacity to complement emerging in vitro technologies, highlighting its contribution to the advancement of safer, more ethical testing practices in biomedical research.