The purpose of this study was to determine whether molecular sieves could be used as a solid sorbent for sampling crotonaldehyde vapors. A simple dynamic dilution apparatus generated concentrations of crotonaldehyde vapors which were sampled with molecular sieve sampling tubes and a constant flow sampler. Laboratory sampling demonstrated quantitative trapping and recovery, and stability of stored samples. Although crotonaldehyde break-through times are decreased by water vapor, it has been demonstrated that sub-ppm levels of volatile aldehydes can be determined under field conditions of high humidity. Further work is needed to quantify the maximum allowable sample volume for crotonaldehyde under such field conditions.