Resveratrol and resveratrol glucoside (piceid) were evaluated in a preformulation stability study. An HPLC assay was used for the analysis of stressed/reference samples. Samples of solid, crystalline material were held under the following conditions: 40 degrees C/75% RH (both open and protected), ambient fluorescent light (open), 70 degrees C (open), and exposed using a light cabinet to achieve ICH conditions for UV/fluorescent light. Both compounds were found to be stable out to 3 months for both accelerated and ambient conditions with negligible degradation. Exposure to UV and fluorescent light under ICH conditions did not significantly degrade the solid materials for UV exposure at 3 times the ICH limit and for fluorescent light exposure at 1 times the ICH limit. The results presented demonstrate crystalline resveratrol and piceid are stable solids. No evidence of oxidation of either material by atmospheric oxidants was seen. The data reported may help to clarify widely held beliefs that resveratrol is unstable and extremely sensitive to oxidation/degradation.