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Highly purifed oil bodies have been isolated from mature seeds of Theobroma cacao. Characterization of the proteins by SDS-PAGE analysis indicated that the purified oil bodies contain a minimum of seven polypeptides, with a polypeptide of approximately 16.1 kDa being the most abundant. At least five of the oil body proteins were in the size range for oleosin proteins (15–30 kDa). Peptide sequencing showed that the approximately 16.1 kDa polypeptide and an approximately 15.0 kDa polypeptide were in fact oleosins, and indicated that an approximately 26.5 kDa polypeptide was probably a caleosin. cDNA encoding the 16.1 kDa polypeptide (TcOleo 16.9) and the 15.0 kDa polypeptide (TcOleo 15.8) were isolated and characterized. Analysis of the protein sequences encoded by these two cDNA indicate that they belong to two different classes of oleosin proteins. Northern blots showed that TcOleo 16.9 and TcOleo 15.8 have relatively similar expression patterns during seed development, although the overall expression of TcOleo 16.9 was significantly higher than that of TcOleo 15.8, in agreement with the observation that the 16.1 kDa polypeptide is more abundant than the 15.0 polypeptide in purified seed oil bodies. The expression of both genes was also induced briefly in the cotyledons during germination. Southern blot analysis showed that TcOleo 16.9 and TcOleo 15.8 were probably single copy genes in the cacao genome. Because the data presented here shows that the oil bodies of T. cacao seeds contain oleosin proteins, it is unlikely that the ‘recalcitrant’ nature of these seeds is due to the absence of oleosin proteins in cacao seed oil bodies as previously proposed. [Copyright &y& Elsevier]