In order to isolate and to analyse the expression of developmentally regulated genes in sunflower, cDNA libraries were constructed using mRNA from 12 or 2O day-old seeds and then differentially hybridized with mRNA from dry seeds and leaves. cDNA encoding major storage proteins (helianthinin and albumin Met-rich), proteinase inhibitor and two other cDNA with unknown function were isolated. The steady state levels of the transcripts, detected with each cDNA, were determined in immature seeds and vegetative tissues at different stages. The accumulation of the five mRNAs was tissue-specific, limited to the mid-maturation stage of seed development. The albumin Met-rich nRNA accumulation occurred relatively later than t}re accumulation of both the helianthinin nRNA and the previously studied HaGS albumin mRNA in sunflower. This indicates that the mRNA synthesis of the two storage protein classes and of different precursors within one protein class is not synchronous. These observations were correlated to the deposit of the different storage protein precursors and are in agreement with a primary control of storage protein gene expression at the Ievel of mRNA transcription. The accumulation of helianthinin transcript was higher in the CANP3 normal variety in comparison with the HOC . high oil and oleic > line. The levels of the albumin Met-rich mRNA were in contrast similar in both lines. This could be in relation with the protein redistribution that is known to accompany the increase of seed dil content in sunflower and agrees with the fact that low oil varieties have higher helianthinin content than high oil varieties. We suggest that the albumin Met-rich fraction is not involved in this protein redistribution.