The objective of this paper is to examine whether the severity and great extent of the 1988 Yellow-stone fires impacted the water quality of two of Yellowstone's major lakes. Analysis of water quality records for Yellowstone and Lewis Lakes collected over a fifteen year period (1976-1991) have shown only a minimal shift in lake water quality following the fires. Though 25 percent of their watersheds were heavily burned, these lakes appear to be large enough to dilute increased inputs and have experienced few lasting effects from the 1988 fires. The relative importance of land-water interactions in affecting the water quality of Yellowstone's large lakes must be viewed in the context of a multitude of other factors, including changing atmospheric deposition and hydrothermal inputs.