This paper reports double-blind observations of volunteers who took 35 kinds of irradiated foods as their main diet for 90 days. The subjects consisted of 70 medical students and 8 staff members in the Shanghai Medical University. They were randomly divided into two groups. One group was supplied with irradiated foods, the other acted as control eating the same food but non-irradiated.,The 35 kinds irradiated foods were listed as follows:,grain: rice, flour, red bean, soybean, peanut;,meat products: pork sausage, preserved beef;,vegetables: potato, cabbage, chinese cabbage, wild rice stem, carrot, mushroom, bamboo shoot, lettuce, arrowhead, cauliflower, sword bean, radish, green pepper, taro, hyacinth bean, white gourd, tomato, young soyabean, water chestnut, lotus root, ginger;,fruits: orange, apple;,dried fruits: dates, longen, lotus seeds;,and others: day lily, dried bean products.,The absorbed dose of irradiation from the processed foods varied from 0.1 to 8.0 kGy. The irradiated foods made up 60.3% of the total intake by weight.,Observations during 90 days indicated that the subjects were all pleased with their diets and no adverse effcts on their health were seen. Clinical and laboratorial examinations included routine blood and urine tests, blood biochemical examinations, hepetic and renal function tests, endocrinologial assays, cellular immunity tests and mutagenetic studies (such as the incedence of polyploid cells, chromosomal structural aberration, rates of sister chromatid-exchanges, micronuclei test, urine Ames test) . These studies showed that the ingestion of these foods are safe for humans.