A study on the effects of the application date of antibiotic on seedlessness and berry size was conduced using 'Muscut of Alexandria'(MOA) and 'Neo Muscut'(NM) grapevines. Two antibiotics were used as seedlessness inducer,streptomycin(SM) and spectinomycine(SE) applied in the concentoration of 200mg/L by dippinng the clusters.The tested of dates of application were 6 and 3 days before full bloom, at full bloom (50% anthesis),and 5days after full bloom.The 3-days before full bloom application gave the highest percentage of seedless berry within each antibiotic in both cultivars.Application after than 3days before full bloon increased production of empty-seeded berries, though the later application was able to increase the berry size and berry weight.