The recruitment of monocytes and their differentiation into macrophages at sites of inflammation are key events in determining the outcome of the inflammatory response and initiating the return to tissue homeostasis. To study monocyte trafficking and macrophage differentiation in vivo we have generated a novel transgenic reporter mouse expressing a Green Fluorescent Protein (GFP) under the control of the human CD68 promoter. CD68-GFP mice express high levels of GFP in both monocyte and embryo-derived tissue resident macrophages in adult animals. The human CD68 promoter drives GFP expression in all CD115+ monocytes of adult blood, spleen and bone marrow and we took advantage of this to directly compare the trafficking of bone marrow derived CD68-GFP monocytes to that of CX3CR1GFP monocytes in vivo using a sterile zymosan peritonitis model. Unlike CX3CR1GFP monocytes, which down regulate GFP expression on differentiation into macrophages in this model, CD68-GFP monocytes retain high level GFP expression for 72 hours following differentiation into macrophages, allowing continued cell tracking during resolution of inflammation. In summary, this novel CD68-GFP transgenic reporter mouse-line represents a powerful resource for analysing monocyte mobilisation and monocyte trafficking as well as studying the fate of recruited monocytes in models of acute and chronic inflammation.