Onion seeds rapidly lose its viability and vigor after short time of harvest, and therefore its germinability largely decline. Consequently, the present investigation was carried out during the period from 2010-2012 in both Plant Tissue Culture Laboratory, Vegetables & Ornamentals Department, Faculty of Agriculture, Mansoura University and greenhouse of a private nursery in production of vegetable transplants, Qlabasho village, El-Dakahlia Governorate to study the effect of Moist-chilling (cold stratification) treatment for four periods (0, 5, 10 and 15 days) at 5 ± 1 ⁰C on improvement of the germination parameters in the laboratory (germination percentage, seedling length, fresh and dry weight and vigor index) of onion seeds cv. “Red Beheri" stored for one or two years and enhancing growth characters (bulblet diameter, transplant length, fresh and dry weights and vigor index) of the subsequent transplants. The obtained results clearly indicated that all germination parameters of onion seeds stored for one or two years (except mean germination time) and also all obtained transplant characters except leaves number were significantly increased in all moist-chilling treatments than control one. The best treatment in this regard was moist-chilling for 15 days whereas the lowest one was control (non chilled seeds).