Representative species of 31 genera belonging to the tribes Paniceae, Andropogoneae, and Arundinelleae of the Panicoideae (Poaceae) were examined for prolamin size variation and immunological relationships to provide some insight into the systematics and evolution of the subfamily. Prolamin polypeptides were resolved by sodium dodecyl sulphate – polyacrylamide gel electrophoresis and the immunological cross-reactivities were measured by ELISA and immunoblotting. The data were analyzed both phenetically and phylogenetically. The Panicoideae contained prolamin polypeptides that ranged in size from about 10 to 35 kDa. Although no definite tribe-specific prolamin patterns were observed, genus-specific polypeptide profiles were evident. The immunological data support the monophyletic origin of the subfamily and its tribes and underscore the ancestral position of the Arundinelleae. Chionachne, subtribe Chionachninae, occupied a position distant from the subfamily that is in agreement with previous studies. The implication of these molecular data on the systematics of the subtribes is discussed. Key words: Poaceae, Panicoideae, protein, prolamin, immunology, systematics, evolution.