The developmental and agronomic characteristics of sunflowers were observed in trials involving 25 hybrids from a factorial cross and 3 commercial varieties, over 2 years, 1986 and 1987. There were significant differences between genotypes for all characteristics except the duration sowing-emergence (table I). From the results, 2 matrices of total linear correlations were calculated between different parameters in order to study relations between developmental stages and earliness at harvest, yield and oil content (tables II and III). The length of developmental phases before and after flowering are independent. The duration emergencephysiological maturity was correlated with the periods before and after flowering, but more closely with the duration flowering-maturity (r = 0.87 **). Earliness at harvest appears correlated with the total duration emergencephysiological maturity (r = 0.74 **), and follows the same pattern, being more especially related to the duration flowering-physiological maturity (r = 0.69 **) than to the duration emergence-flowering (r = 0.54 *). Of the morphological characters observed, most do not provide any useful indication concerning earliness; only leaf number shows a significant correlation with emergence-flowering and emergence-maturity. In contrast, yield is significantly correlated with morphological characters which vary with plant vigour, such as head and basal stem diameter and plant height. For the components directly determining yield, seed number per capitulum appears more important than 1 000 seed weight. In the conditions of the trials, yield appears most related to characters determined before flowering. Oil content is not closely linked with other characters, except lateness to some extent. It is concluded that since earliness at harvest depends on the sum of all the vegetative stages, more particularly those after flowering, no juvenile character provides a satisfactory forecast. Earliness can only be determined by end of cycle observations on seed maturation. However, the absence of any significant correlation between yield and earliness suggests that it should be possible to select for high yielding early sunflowers.