In 1995, a study was carried out to evaluate the changes in source-sink relationships induced in the vine by CPPU treatment. Two weeks after full bloom CPPU (20 ppm) was sprayed to run-off on fruitlets inside the canopy of vines having a different fruit load (untreated plants were used as control). The different fruit load affected the final fruit weight. However, in all the vines CPPU determined a significant increase in fruit size and hence in yield per vine. The vegetative development of vines, estimated by weighing the pruned material, was similar in CPPU treated and control vines. In the season following treatment, the percentages of bud-burst and fertile buds were affected by the different vine fruit load but not by CPPU treatment. The results indicate that CPPU improved the ability of fruits to attract and use assimilates. CPPU increased the allocation of assimilates in the fruits without significantly affecting other competing sinks such as vegetative apex, buds and storage tissues. These results can be explained by the timing of the higher fruit growth and dry matter accumulation induced by CPPU.