Microglia use digestive exophagy to partially degrade, extracellularly, Alzheimer's amyloid-beta aggregates that are too large to be phagocytosed. Here, we present a protocol to quantify this mechanism in cell culture. We describe steps for extracting primary microglial cells and preparing amyloid-beta model aggregates. We then detail procedures for measuring lysosomal exocytosis toward, and extracellular degradation of, these deposits using quantitative fluorescence microscopy. We also provide guidance on quantifying the data using digital image analysis. For complete details on the use and execution of this protocol, please refer to Jacquet et al.1.