Thirty male weanling WAK strain rats were divided rondomly into 6 groups. All of the diets were pure synthetics according to AOAC. The 1st, 2nd and 3rd group were given diets containing 6, 15 and 24 ppm of zinc respectively, and 10% protein for all three groups, on the other hand, the 4th, 5th and 6th group were given diets containing 5% 10% and 20% of protein respectively, and 15 ppm of zinc.After feeding in stainless steel cage singly for 50 days rats were given intubately solution of 65Zn containing 1.5 ?Ci per 100g of body weight. Then the faeces and urine of rats were collected on 5 consecutive days, and the zinc absorption and retention of all of the tested rats were determined with method of 65Zn as tracer. The results indicated that. (1) The zinc absorption and retention of rats fed on the lowest zinc level were increased significantly. (2) The zinc absorption and retention of rats fed the lowest protein level were decreased significantly, and were improved clearly by increasing protein intake level. (3) The urine excretion of zinc is very low and can not be used as an index in zinc metabolism research. The methodology for determining zinc absorption and retention in organism with method of 65Zn and total zinc is discussed.