Sunflower chlorotic mottle virus (SuCMoV) was detected in several sun flower (Helianthus annuus L.) growing areas, causing a disease characterized by systemic chlorotic mottling. Symptom severity depended on several factors, including the ontogenetic stage at which infections occur. The objective of this study was to determine the effects of artificial infections with SuCMoV at different ontogenetic stages on agronomic yield characters (plant height, stem and capitulum diameters, achene yield, seed width and length, weight of 1000 seeds and oil content). Sunflower seeds of commercial hybrids Dekalb 4030, Contiflor 3N, and ACA 884 were sown in a split plot design with four replications, which were mechanically inoculated with SuCMoV at four growth stages. A negative (non-inoculated) control was included in the experiment. Virus infection was detected by symptoms and by double antibody sandwich enzymelinked immunosorbent assay (DAS-ELISA). Virus infections at all stages significantly reduced plant height (16-39%), stem diameter (21-51%), capitulum diameter (27-57%), achene yield (58-87%), seed width (13 -15%), seed length (10-16%) and weight of 1000 seeds (26-28%) compared with healthy controls, independent of hybrid tested. Oil content determined by magnetic nuclear resonance showed no significant differences among treatments.