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The 36 MODIS spectral bands, with wavelengths ranging from 0.41 mu m to 14.2 mu m, are distributed on four focal plane assemblies: visible (VIS), near-infrared (NIR), short-and mid-wave infrared (SMIR), and long-wave infrared (LWIR). The MODIS reflective solar bands (RSB) are calibrated on-orbit using a solar diffuser (SD), with its reflectance degradation monitored using a solar diffuser stability monitor (SDSM). The Terra MODIS SD degradation at 0.936 mu m, as measured by the SDSM, is 2.4% after 14 years on-orbit. The Aqua MODIS SD degradation at 0.936 mu m is 0.6% after 12 years on-orbit. The SWIR bands with spectral wavelengths centered at 1.24 mu m (band 5), 1.37 mu m (band 26), 1.64 mu m (band 6), and 2.13 mu m (band 7), are beyond the SDSM wavelength coverage (0.412 mu m to 0.936 mu m). Consequently, the gain of the SWIR bands is computed without factoring in the possible degradation of the SD. A technique to monitor the long-term stability of the MODIS SWIR bands is developed using pseudo-invariant desert targets. Results indicate a long-term drift of up to 1.5% of band 5 of Terra MODIS. The long-term stability of other Terra MODIS SWIR bands is seen to be within 0.5%. Similar results for Aqua MODIS indicate no observable drift, with changes within 0.5%. An implementation strategy to account for this correction in the MODIS Level 1 B (L1B) is also discussed.