In order to develop a commercial storage method cf onions by irradiation combined with natural low temperature, two local varieties of onions, precocious species and late ripening, were stored at natural low temperature storage room(450×650×250㎝H.; year-round temperature change, 2∼17℃; R.H., 80∼85%) on batch scale following irradiation with optimum dose level. Precocious and late varieties were all sprouted after five to seven months storage, whereas 10∼15 Krad irradiated precocious variety was 2∼4% sprouted after nine months storage, but sprouting was completely inhibited at the same dose for late variety. The extent of loss due to rot attack after ten months storage were 23∼49% in both control and irradiated group of precocious variety but those of late variety were only 4∼10%. The weight loss of irradiated precocious variety after ten months storage was 13∼16%, while that of late variety was 5.3∼5.9% after nine months storage. The moisture content, during whole storage period, of two varieties were 90∼93% with negligible changes. The total sugar content differed little with varieties and doses immediately after irradiation, but decreased by the elapse of storage period. 33.6% of its content was decreases: in control and 12.5% in irradiated group but 20∼26% decreased in both control and irradiated group of late variety after nine months storage. No appreciable change was observed immediately after irradiation irrespective of variety and dose, but decreased slightly with storage. Ascorbic acid content of precocious variety was increased slightly with dose immediately after irradiation, but those of late variety decreased slightly. Ascorbic acid content were generally decreased during whole storage period. An economical preservation method of onions appliable to late variety, would be to irradiate onion bulbs at dose range or 10∼15Krad followed by storage at natural low temperature storage room.