When characterizing the anticipated monotonic decay of Bragg reflections in selected area electron diffraction (SAED) patterns from molecular microcrystals, we observed anomalous fluctuations in Bragg reflection intensities arising from apparently static crystals. To measure these fluctuations, we illuminated static sub-micron thick crystals of five distinct small molecules (biotin, Cu(II)-serine, Zn(II)-methionine, Zn(II)-histidine, and Co(II)-meso-tetraphenyl porphyrin) with low flux (0.01 e -/Å 2 /s) 200 kV or (0.04 e -/Å 2 /s) 300 kV electron beams, while continuously recording selected area diffraction patterns from each. Across these dose series, static crystals exhibited the overall characteristic decay in Bragg reflections, with their rates of decay differing depending on their sensitivity to electron beam damage (Supplementary Table ). However, most crystals also displayed unpredictable non-monotonic changes in measured intensities for a subset of Bragg reflections across varying resolutions. The intensity of this effect reflected the beamsensitivity of crystals, where over the course of as little as 2 e -/Å 2 total exposure, reflections could newly enter or completely exit the excitation condition. The overall effect was distinct from the monotonic, resolution-dependent decay in reflection intensities due to radiolytic damage. In contrast, the likelihood of a reflection to exit excitation in this way appeared to be unrelated to its resolution (Fig. ).