14CO2 was supplied under laboratory conditions to the terminal leaves of peach and apricot shoots taken from orchard trees over the period from flowering to fruit maturity. The distribution of 14C assimilates along the shoot, and the patterns of deposition within the developing fruit were recorded on X-ray film. In both peach and apricot shoots, the terminal leaves, soon after emergence, exported assimilates to adjacent fruit which competed successfully with nearby expanding leaves, although isolated leaves (in peach) were capable of importing. At a more advanced stage only the fruits imported assimilates from the terminal leaves, and the labelled substrates were deposited in both flesh and inner seed structures despite the hardened stone. The fruit continued to accumulate 14C photosynthate even when completely ripe. Following fruit removal, export from the terminal leaves on the peach shoot was minimal, and labelled photosynthate was detected only in the main stem; whereas in apricot shoots, mature lower leaves showed extensive import of current assimilates.