This study was performed at Seed Technology Research Unit, Mansoura. Seed Technology Research Department, ARC, to evaluate the efficiency of treating onion seed with Vitavax-thiram200,Bio-zeid,Bio-arec and Salcilic acid on seed germination, seedling vigor and seed-borne fungi of the tested cultivars(Giza Red, Giza 20,Giza 6 and Farmer seed) by blotter method.Alternaria sp., Aspergilus spp., Botrytis allii, Drechslera sp., Epicoccum sp., Fusarium spp., Pencillium spp., Rhizoctonia solani and Rhizopus sp.were associated with onion seeds.Treatments of onion seeds with the Fungicide (Vitavax-200),  Biotic (Bio-arec and Bio-zeid) and Abiotic (Salicylic acid) showed that the fungicidal treatment Vitavax-200 with recommended doses eliminated the mentioned fungi completely, but gave the lowest mean percentage of germination (MPG). Biotic gave the highest of MPG with all cultivars as compared with the control. Abiotic played an important role in enhancing seed viability with all cultivars and increased seedling length, especially root length when applied as seed soaking. Cultivar Giza 20 gave the highest (MPG) and vigorous followed by cv. Giza Red, cv. Farmer seed and cv. Giza 6. Bio-arec and Bio-zeid gave protection and less numbers of total pathogenic fungi of onion seed with high significant, salicylic acid reduced of diseases incidence in seedlings.