Powder samples of naturally dried and spray processed spriulina polysacchrides were irradiated to different doses from 1.2 to 13.5 kGy by ,60,Co γ-rays. Microbial tests were performed and the nutritional compositions were measured. The results showed that for decontamination down to 1.0×10,4,cfu/g of total number of bacteria and 25cfu/g of fungi, the minimum doses were 10.1kGy and 2.9kGy for the naturally dried powder and spray processed powder, respectively. However, 10.1kGy irradiation caused over 40% loss of carotene in the naturally dried powder, whereas 2.9kGy irradiation caused just 15% loss of .carotene in the spray processed powder.