Endo-beta-1,4-D-glucanases (EGases) are a widespread and vital group of glycosyl hydrolases that generally break the beta-1,4-glucosyl linkages. Studies of plant EGases have mainly been concentrated on vegetative growth, while little is currently known about their role in reproductive processes. Using the GUS reporter aided analysis of promoter activities, we identified the expression patterns of two putative Arabidopsis EGases genes (At3g43860 and At4g39000) whose promoters conferred specific localization of the GUS activity in reproductive organs. We found that At3g43860, which is similar to KOR in its protein structural organization, is expressed in mature pollen and the pollen tube, implying that it may have a role in pollen and pollen tube growth. At4g39000 was found to be activated in the developing ovules and seeds, especially at the micropylar end of the inner integuments and nucellus in a proximal-distal pattern. Our results suggested that the two EGases play specific roles in Arabidopsis sexual reproduction.