The cotyledons of developing bean (Phaseolus vulgaris L.) seeds rapidly synthesize and accumulate the storage globulin, phaseolin1, which seems to be encoded as a small multigene family2,3. Phaseolin from the cultivar ‘Tendergreen’ has been resolved electrophoretically into three components (of differing molecular weights), designated α (51,000), β (48,000) and γ (45,500). The in vitro synthesis of phaseolin has been investigated previously using a cell-free translation system derived from wheat germ4. The in vitro products did not co-migrate with the authentic polypeptides, the differences apparently being due to the lack of glycosylation of the primary transcripts. We have now used Xenopus oocytes to translate mRNA from bean cotyledons and find that phaseolin is synthesized in a glycosylated form very similar to authentic phaseolin and is transported into the membrane fraction of the cells.