In this study we initiated a proteomic investigation of the maize thylakoid membrane by using a shotgun proteomic approach based on LC-MS(E). A total of 34 maize thylakoid membrane proteins were identified, the majority of which are primarily involved in photosynthesis, including the light-reaction and carbon assimilation. It is noteworthy that all of the core subunits of the Photosystem II were identified in our search. Proteins involved in other processes, such as iron storage, were also detected in our study. The quantity of each identified protein was also determined. Of interest, we discovered that the amount of the three ATP synthase subunits were not equivalent, suggesting that these proteins perform other functions in addition to ATP synthesis. To our knowledge this is the first extensive proteomic investigation of the maize thylakoid membrane, and will likely enable further study of maize photosynthesis and chloroplast development.