The objective of this work was to determine the number of reproductive structures in relation to the vascularization of sunflower capitulum in three sectors: outer, middle and center, and in four development stages: E2 (early floral button), E4 (late floral button), F3.2 (beginning flowering) and M0 (end flowering) according to the CETIOM code. Seeds of Dekalb G100 sunflower hybrid were sown at 72.000 pl/ha density and the capitula gathered at the indicated stages. At each stage, significant increases were noticed in the reproductive structures number from the outer sector to the center of capitulum. The number of vascular bundles per unit of surface showed a significant decrease from the outer sector to the center at E2 and E4 stages and a tendency to become stable at F3.2 and M0. The obtained values of surface covered by phloem per cm2 of capitulum, decreased remarkably from the outer sector to the center at E4 stage while at F3.2 and M0 minor but still important decreases were observed. The statistical analysis made on reproductive structures number in relation to vascular bundles number and surface covered by phloem showed low and insignificant correlations, respectively.