Introduction: Conversion to organic vineyards is a critical period. The changes operated in the crop management sequence can impact the yield components and consequently the yield. Yield losses can occur temporally or more permanently if adaptations are not adequate. In this work, we performed a regional yield diagnosis to assess yield dynamics during the conversion to organic vineyard. Material and methods: From 2013 to 2016, we followed a network of 46 in conversion and conventional winegrower plots (from 10 to 15 plots each year) situated in Southern France and planted with Grenache wine. It corresponded to 8 plots in conventional farming, 12 in the first year of conversion to organic farming, 15 in the second year and 12 in the third year.proceeded from a diachronic perspective taking into account inter-annual variability. We followed the yield elaboration during the 2-year development period of the grapevine. To do so we monitored 30 grapes in each plot from inflorescence appearance to harvest. We assessed the three main yield components which successively are built during the 2 years of the development period (Guilpart et al., 2014…): the number of clusters, number of mature berries per cluster and the average mature berry weight. Results: Results showed that the conversion to organic farming affected agronomic performance. Yield elaboration was impacted. We noted a significant decrease of the number of inflorescences, the number of berries per cluster and the average mature berry weight during the first two years of the conversion. The maximum impact on the number of inflorescences per plant was observed the second year of the conversion. This could be explained by the fact that the number of inflorescences was determined the year before, which was the first year of conversion when the changes in practices were operated. The number of berries per cluster and the average mature berry weight were impacted the first year and the second year of the conversion. The third year of the conversion the initial level before conversion was reached again and sometimes exceeded in some situations. Finally, the yield and yield achievement dynamics were impacted by the conversion to organic farming. A yield loss was observed the first and second year of the conversion. The impact of the conversion was limited to these two years. Discussion and conclusion: We observed an effect of the conversion on the yield elaboration the first and second year of the conversion. This impact was limited in time. In fact the third year of the conversion, yield reached again the level before conversion. Thus learning and adaptations were established the third year of conversion. Next step will be to link these agronomics results to the factors explaining the yield decrease during the conversion to organic farming.