Seven sunflower genotypes comprising of populations and hybrids showing differential sporophytic reaction to Alternaria leaf and stem blight were studied for their gametophytic reaction to pathogen culture filtrate. The sunflower pollen grains germinate well in the liquid medium and give good pollen tube growth in the absence of the culture filtrate. The addition of increasing concentrations of culture filtrate to medium significantly reduced the pollen germination and tube growth in all the genotypes. The reduction in pollen germination and tube growth in vitro due to culture filtrate was more in highly susceptible genotypes L-101 and Morden than the moderately resistant genotypes Acc. nos. 1229, 180 and ISFH-306. Pretreating the stigma and style with the culture filtrate before pollination reduced the number of pollen grains germinating compared to untreated control suggesting toxin stress can be created on the stigmatic surface before pollination. There was correspondence between pollen germination on stressed stigma (in vitro) and sporophytic reaction of the genotype suggesting pollen grain having resistance would germinate on the stressed stigma and fertilise the ovule achieving selective fertilisation. The correlation analysis indicated that there is a negative relation between sporophytic per cent disease index value and gametophytic parameters such as in vitro and in vivo pollen germination, culture filtrate required to inhibit 50% pollen germination and pollen tube growth. The association between pollen and the sporophytic reaction to the disease indicate the possibility of rapid screening of a large number of genotypes by means of pollen assay as an alternate technique with regard to sporophytic disease index in sunflower. The study also indicate the possibility of pollen selection before fertilisation to achieve rapid improvement in disease resistance.